java double精度丟失問題

public static double getRound(double d, double n) {
		d = d * Math.pow(10, n);
		if(d>0){
			d += 0.5d;
		}else{
			d -= 0.5d;
		}
		d = (long) d;
		d = d / Math.pow(10d, n);
		return d;
	}