sales = float(input('Enter the amount of sales (or -1 to stop): '))
while sales != -1:
    comm_rate = float(input('Enter the commission rate: '))
    
    commission = sales * comm_rate
    
    print('The commission is $'+format(commission, '.2f'))
            
    sales = float(input('Enter the amount of sales (or -1 to stop): '))

print("This will show only after the loop is over")