Sub Total – This is the running total of the current bill. The sub total is a summation of all the items within the order, before a blanket surcharge or discount is added to the entire amount.
Surcharge – Displays the current surcharge amount added to the entire bill.
Discount – This line displays the current discount subtracted from the entire cost of the bill.
Total – Displays the total amount of the bill that is to be charged to the customer. This includes any surcharging or discounts that may or may not be added to the bill.