Static public double arrondir(double value, int n) {
double r = (Math.round(value * Math.pow(10, n))) / (Math.pow(10, n));
return r;
}

static public Double arrondir(Double value, int n) {
double r = (Math.round(value.doubleValue() * Math.pow(10, n))) / (Math.pow(10, n));
return new Double(r);
}

==>Exemple d'utilisation : arrondir(new Double(0.004),2) ;//arrondi à la 2eme décimale

Empêche des erreurs

public class RoundTest
{   
    public static void main(String[] args)
    {
        double num = myRound(15.6666666, 2);
        System.out.println( num ); //it’s a double
        
        String str = myRound(15.6666666, "0.00");
        System.out.println( str ); //it’s a String
    }
    
    private static double myRound(double value, int decimalPlaces)
    {
        if(decimalPlaces < 0) { return value; }
        double augmentation = Math.pow(10, decimalPlaces);
        return Math.round(value * augmentation) / augmentation;
    }
    
    private static String myRound(double value, String format)
    {
        if(format == null  ||  format.length() <= 0) { return String.valueOf(value); }
        return new DecimalFormat(format).format(value);
    }
}