How to write a program count total prices

Hi. all

I've got a assignment to write a program that count total prices of 8 costumers.

class PriceCalculator{
    public void method(double quantity)
    {
    double result;
        if(quantity < 5)
        {
            result = 2.00*quantity;
            System.out.printf(" is: %s",result);
        }
        if(quantity >= 6 & quantity <= 10)
        {
            result = 2.00*quantity*95/100;
            System.out.printf(" is: %s",result);
        }
        if(quantity >= 11 & quantity<= 15)
        {
            result = 2.00*quantity*90/100;
            System.out.printf(" is: %s",result);
        }
        if(quantity >= 16 & quantity<= 20)
        {
            result = 2.00*quantity*85/100;
            System.out.printf(" is: %s",result);
        }
        if(quantity >20)
        {
            result = 2.00*quantity*80/100;
            System.out.printf(" is: %s",result);
        }
    }
}

Second class
import java.util.Scanner;
public class PriceCalculatorTest{
    public static void main(String[] args){
        double enterQ;
        System.out.println("*****WELCOMETO PRICE CALCULATOR FOR PURCHANGSING MILKS*****");
        for(int counter = 1; counter <=8; ++counter)
        {
        Scanner input = new Scanner(System.in);
        PriceCalculator m = new PriceCalculator();
        System.out.printf("Enter the Name for Customer %s: ",counter);
        String name = input.nextLine();
        System.out.printf("Enter the number of cartons for Customer %s: ",counter);
        enterQ = input.nextInt();
        System.out.printf("The price for Customer - %s",name);
        m.method(enterQ);
        System.out.println();
        System.out.println("---------");

        }

    }
}

Is there anyone,please help me.. Really thanks a lot