Calculating Commission With Loops / If Else Statements And JOptionPane

SalesMan receives 200$ a week plus 9% of commission on the items he had sold that week

item 1 = 5.00
item 2 = 10.00
item 3 = 1.00
item 4 = 25.00

My code : (((I honestly dont know how to loop it... it must ask "What item did you purchase, and have the user input the number of item they purchased THAN looped back to ask again what item did they purchase untill they hit -1 to exit the loop))

import javax.swing.JOptionPane;
public class ControlStructure{
public static void main(String [] args){
double item1 = 5.00;//item 1 price
int quan1 = 0;
double total1 = 0;

[Code] .....