双增值是不合适的

Question

这里的问题是当我添加amountbeforetax是68.0，税额为14.96时，它给我amountWithTax等于82.96000000000001，但当我加税时金额是14.97或14.95,14.98它给了我正确的值。

这里有什么问题？为什么它会给我这样的结果？

      public class Calc {
       public static void main(String[] args) {
        double discountAmount = 0;
        double amountBeforeTax = 0;
        double amountWithTax = 0;
        double taxAmount = 0;

        amountBeforeTax = 68.0;
        System.out.println("amountBeforeTax "+amountBeforeTax);
        taxAmount = 14.96;
        System.out.println("taxAmount "+taxAmount);
        amountBeforeTax-= discountAmount;
        System.out.println("amountBeforeTax after discount "+ amountBeforeTax);
        amountWithTax = amountBeforeTax + taxAmount;
        System.out.println("amountWithTax "+ amountWithTax);
    }
}