Rounding

Round.java

public class Round {
    
    public static void main(String[] args) {
        System.out.println(round(3.124, 2));
    }
    
    static double round(double x, int n) {
        double y = x * tenToN(n);
        y = Math.round(y);
        return y / tenToN(n);
    }
    
    static double tenToN(int n) {
        if (n > 0) {
            return 10 * tenToN(n-1);
        }
        else {
            return 1;
        }
    }
}