diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/ext/OpenGotha.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/ext/OpenGotha.kt
index 4719356..1c759b4 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/ext/OpenGotha.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/ext/OpenGotha.kt
@@ -85,7 +85,8 @@ object OpenGotha {
                 seedSystem2 = parseSeedSystem(pairParams.paiMaSeedSystem2 ?: "SPLITANDSLIP"),
                 additionalPlacementCritSystem1 = Criterion.valueOf(pairParams.paiMaAdditionalPlacementCritSystem1.uppercase()),
                 additionalPlacementCritSystem2 = Criterion.valueOf(pairParams.paiMaAdditionalPlacementCritSystem2.uppercase().replace("NULL", "NONE")),
-                mmsValueAbsent = genParams.genMMS2ValueAbsent.toDouble() / 2.0
+                mmsValueAbsent = genParams.genMMS2ValueAbsent.toDouble() / 2.0,
+                roundDownScore = genParams.genRoundDownNBWMMS.toBoolean()
             ),
             secondary = SecondaryCritParams(
                 barThresholdActive = pairParams.paiSeBarThresholdActive.toBoolean(),
@@ -304,7 +305,9 @@ object OpenGotha {
                 ).uppercase(Locale.ROOT)
             }" genMMS2ValueAbsent="${
             (tournament.pairing.pairingParams.main.mmsValueAbsent * 2).roundToInt()
-            }" genMMS2ValueBye="2" genMMZero="30K" genNBW2ValueAbsent="0" genNBW2ValueBye="2" genRoundDownNBWMMS="true" komi="${tournament.komi}" location="${tournament.location}" name="${tournament.name}" nbMovesCanTime="${tournament.timeSystem.stones}" numberOfCategories="1" numberOfRounds="${tournament.rounds}" shortName="${tournament.shortName}" size="${tournament.gobanSize}" stdByoYomiTime="${tournament.timeSystem.byoyomi}"/>
+            }" genMMS2ValueBye="2" genMMZero="30K" genNBW2ValueAbsent="0" genNBW2ValueBye="2" genRoundDownNBWMMS="${
+                tournament.pairing.pairingParams.main.roundDownScore
+            }" komi="${tournament.komi}" location="${tournament.location}" name="${tournament.name}" nbMovesCanTime="${tournament.timeSystem.stones}" numberOfCategories="1" numberOfRounds="${tournament.rounds}" shortName="${tournament.shortName}" size="${tournament.gobanSize}" stdByoYomiTime="${tournament.timeSystem.byoyomi}"/>
             <HandicapParameterSet hdBasedOnMMS="${tournament.pairing.pairingParams.handicap.useMMS}" hdCeiling="${tournament.pairing.pairingParams.handicap.ceiling}" hdCorrection="${tournament.pairing.pairingParams.handicap.correction}" hdNoHdRankThreshold="${displayRank(tournament.pairing.pairingParams.handicap.rankThreshold)}"/>
             <PlacementParameterSet>
             <PlacementCriteria>
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt
index b28e94a..e30b440 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/model/Pairing.kt
@@ -51,6 +51,7 @@ data class MainCritParams(
     val additionalPlacementCritSystem1: Criterion = Criterion.RATING,
     val additionalPlacementCritSystem2: Criterion = Criterion.NONE,
     val mmsValueAbsent: Double = 0.5,
+    val roundDownScore: Boolean = true
 ) {
     enum class DrawUpDown { TOP, MIDDLE, BOTTOM }
     enum class SeedMethod { SPLIT_AND_FOLD, SPLIT_AND_RANDOM, SPLIT_AND_SLIP }
@@ -243,7 +244,8 @@ fun MainCritParams.Companion.fromJson(json: Json.Object, localDefault: MainCritP
     seedSystem2 = json.getString("secondSeed")?.let { MainCritParams.SeedMethod.valueOf(it) } ?: localDefault?.seedSystem2 ?: default.seedSystem2,
     additionalPlacementCritSystem1 = json.getString("firstSeedAddCrit")?.let { Criterion.valueOf(it) } ?: localDefault?.additionalPlacementCritSystem1 ?: default.additionalPlacementCritSystem1,
     additionalPlacementCritSystem2 = json.getString("secondSeedAddCrit")?.let { Criterion.valueOf(it) } ?: localDefault?.additionalPlacementCritSystem2 ?: default.additionalPlacementCritSystem2,
-    mmsValueAbsent = json.getDouble("mmsValueAbsent") ?: localDefault?.mmsValueAbsent ?: default.mmsValueAbsent
+    mmsValueAbsent = json.getDouble("mmsValueAbsent") ?: localDefault?.mmsValueAbsent ?: default.mmsValueAbsent,
+    roundDownScore = json.getBoolean("roundDownScore") ?: localDefault?.roundDownScore ?: default.roundDownScore
     )
 
 fun MainCritParams.toJson() = Json.Object(
@@ -259,7 +261,8 @@ fun MainCritParams.toJson() = Json.Object(
     "secondSeed" to seedSystem2,
     "firstSeedAddCrit" to additionalPlacementCritSystem1,
     "secondSeedAddCrit" to additionalPlacementCritSystem2,
-    "mmsValueAbsent" to mmsValueAbsent
+    "mmsValueAbsent" to mmsValueAbsent,
+    "roundDownScore" to roundDownScore
 )
 
 fun SecondaryCritParams.Companion.fromJson(json: Json.Object, localDefault: SecondaryCritParams? = null) = SecondaryCritParams(
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt
index 41a43f9..b005731 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/BaseSolver.kt
@@ -15,8 +15,11 @@ import java.io.PrintWriter
 import java.text.DecimalFormat
 import java.util.*
 import kotlin.math.abs
+import kotlin.math.ceil
+import kotlin.math.floor
 import kotlin.math.max
 import kotlin.math.min
+import kotlin.math.roundToInt
 
 sealed class BaseSolver(
     val round: Int, // Round number
@@ -492,6 +495,13 @@ sealed class BaseSolver(
         return pairable.rank
     }
 
+    fun roundScore(score: Double): Int {
+        val epsilon = 0.00001
+        // Note: this works for now because we only have .0 and .5 fractional parts
+        return if (pairing.main.roundDownScore) floor(score + epsilon).roundToInt()
+        else ceil(score - epsilon).roundToInt()
+    }
+
     open fun HandicapParams.clamp(input: Int): Int {
         var hd = input
         if (hd >= correction) hd -= correction
diff --git a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt
index f0e97be..9f37120 100644
--- a/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt
+++ b/api-webapp/src/main/kotlin/org/jeudego/pairgoth/pairing/solver/MacMahonSolver.kt
@@ -28,7 +28,7 @@ class MacMahonSolver(round: Int,
 
     override fun HandicapParams.pseudoRank(pairable: Pairable): Int {
         if (useMMS) {
-            return (pairable.mms + Pairable.MIN_RANK).toInt()
+            return roundScore(pairable.mms + Pairable.MIN_RANK)
         } else {
             return pairable.rank
         }