diff --git a/htdocs/core/lib/price.lib.php b/htdocs/core/lib/price.lib.php
index ec5ff384592..14fbeead6b8 100644
--- a/htdocs/core/lib/price.lib.php
+++ b/htdocs/core/lib/price.lib.php
@@ -198,8 +198,13 @@ function calcul_price_total($qty, $pu, $remise_percent_ligne, $txtva, $uselocalt
 	}
 
 	// initialize total (may be HT or TTC depending on price_base_type)
-	$tot_sans_remise = $pu * $qty * ($progress / 100);
-	$tot_avec_remise_ligne = $tot_sans_remise * (1 - ((float) $remise_percent_ligne / 100));
+	if ($remise_percent_ligne && getDolGlobalString('MAIN_APPLY_DISCOUNT_ON_UNIT_PRICE_THEN_ROUND_BEFORE_MULTIPLICATION_BY_QTY')) {	// MAIN_APPLY_DISCOUNT_ON_UNIT_PRICE_THEN_ROUND_BEFORE_MULTIPLICATION_BY_QTY can be 'MU', 2, ...
+		$tot_sans_remise = $pu * $qty * ($progress / 100);
+		$tot_avec_remise_ligne = (float) price2num($pu * (1 - ((float) $remise_percent_ligne / 100)), getDolGlobalString('MAIN_APPLY_DISCOUNT_ON_UNIT_PRICE_THEN_ROUND_BEFORE_MULTIPLICATION_BY_QTY')) * $qty * ($progress / 100);
+	} else {
+		$tot_sans_remise = $pu * $qty * ($progress / 100);
+		$tot_avec_remise_ligne = $tot_sans_remise * (1 - ((float) $remise_percent_ligne / 100));
+	}
 	$tot_avec_remise       = $tot_avec_remise_ligne * (1 - ((float) $remise_percent_global / 100));
 
 	// initialize result array