def decimal(number, places):
    return ('{:0.' + str(places) + 'f}').format(round(number, places))

def refund_calc(totes, bottles, beercrates, beerbottles):
    refund = (4 * totes) + (0.25 * bottles) + (3.90 * beercrates) + (0.10 * beerbottles)
    #return '{:0.2f}'.format(round(refund, 2))
    return decimal(refund, 2)

Customer_1 = [3, 8, 0, 0]
print(refund_calc(*Customer_1))

Customer_2 = [3, 8, 1, 0]
print('total refund for customer 2 will be', refund_calc(*Customer_2))