Forward mode calculates the tip from a percentage. Reverse mode finds the tip percentage from the bill and amount paid.
Choosing a service type loads the typical US tip range for that category.
Adjusts the suggested tip percentage within the typical range for your service type.
On: tip is calculated on the pre-tax bill. Off: tip is calculated on (bill + tax).
Rounds the per-person amount up to the next whole dollar for easy cash payment.