Sales Tax And Service Charge To Ticket Total Only


I seem to be having a major problem. I have service charge of 5% and Sales tax of 17%. The issue i am facing is that i need both to be applied to the total ticket amount separately.

Currently my pos is adding service charge 5% to the ticket total which is correct, how ever the sales tax 17% is being applied to both the ticket total + Service charge. I need the sales tax to apply directly to the ticket total amount and not to the ticket total and service charge. I have attached the screen shot.Tax