Preisrechner: Rappenrundung im Backend und Rabatt-Rechner im Web

agentd task ad07191c406d4ea496b0b18db826651e

tests/Prices.Tests/PriceCalculatorTests.cs

@@ -33,4 +33,25 @@ public sealed class PriceCalculatorTests
     {
         Assert.Throws<ArgumentOutOfRangeException>(() => PriceCalculator.ApplyDiscount(100m, 101m));
     }
+
+    [Fact]
+    public void ApplyDiscount_99_90_with_10_percent_rounds_to_89_90()
+    {
+        // 99.90 * (1 - 10/100) = 89.91 → rounded to nearest 0.05 = 89.90
+        Assert.Equal(89.90m, PriceCalculator.ApplyDiscount(99.90m, 10m));
+    }
+
+    [Fact]
+    public void ApplyDiscount_10_with_33_percent_rounds_correctly()
+    {
+        // 10 * (1 - 33/100) = 6.70 → 6.70 is already a multiple of 0.05
+        Assert.Equal(6.70m, PriceCalculator.ApplyDiscount(10m, 33m));
+    }
+
+    [Fact]
+    public void ApplyDiscount_5_55_with_10_percent_rounds_to_5_00()
+    {
+        // 5.55 * 0.9 = 4.995 → rounded to nearest 0.05 = 5.00
+        Assert.Equal(5.00m, PriceCalculator.ApplyDiscount(5.55m, 10m));
+    }
 }