我正在为我的中学课程用Java写一个基本的命令行程序。我们现在仅使用变量。用于计算购买后找零的任何类型的纸币和硬币的数量。这是我的程序：

class Assign2c {
    public static void main(String[] args) {
        double cost = 10.990;
        int paid = 20;
        double change = paid - cost;
        int five, toonie, loonies, quarter, dime, nickel, penny;

        five = (int)(change / 5.0);
        change -= five * 5.0;

        toonie = (int)(change / 2.0);
        change -= toonie * 2.0;

        loonies = (int)change;
        change -= loonies;

        quarter = (int)(change / 0.25);
        change -= quarter * 0.25;

        dime = (int)(change / 0.1);
        change -= dime * 0.1;

        nickel = (int)(change / 0.05);
        change -= nickel * 0.05;

        penny = (int)(change * 100);
        change -= penny * 0.01;

        System.out.println("$5   :" + five);
        System.out.println("$2   :" + toonie);
        System.out.println("$1   :" + loonies);
        System.out.println("$0.25:" + quarter);
        System.out.println("$0.10:" + dime);
        System.out.println("$0.05:" + nickel);
        System.out.println("$0.01:" + penny);
    }
}

它应该可以正常工作，但在最后一步还有0.01美元的余款时，便士数应该为1，而应为0。进入代码并将更改值输出到控制台几分钟后，我发现在change =0.01的最后一步，它将更改为0.009999999999999787。为什么会这样呢？