BAEL-2154 - BigDecimal and BigInteger article.

java-numbers/src/main/java/com/baeldung/maths/BigDecimalDemo.java

@@ -0,0 +1,27 @@
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+
+public class BigDecimalDemo {
+
+    /** Calculate total amount to be paid for an item rounded to cents..
+     * @param quantity
+     * @param unitPrice
+     * @param discountRate
+     * @param taxRate
+     * @return
+     */
+    public static BigDecimal calculateTotalAmount(BigDecimal quantity,
+        BigDecimal unitPrice, BigDecimal discountRate, BigDecimal taxRate) { 
+        BigDecimal amount = quantity.multiply(unitPrice);
+        BigDecimal discount = amount.multiply(discountRate);
+        BigDecimal discountedAmount = amount.subtract(discount);
+        BigDecimal tax = taxRate.multiply(taxRate);
+        BigDecimal total = discountedAmount.add(tax);
+
+        // round to 2 decimal places using HALF_EVEN
+        BigDecimal roundedTotal = total.setScale(2, RoundingMode.HALF_EVEN);
+        
+        return roundedTotal;
+    }
+
+}