I want to create a cell that takes a total, and multplies it by 15%, however,
if the 15% is less than twenty, I want the amount to be 20.

I.E.-- subtotal is $95.00, so 15% would be $14.25. However I want the cell
to show$20.00.
I.E.-- sutotal is $300.00, so 15% would be $45.00. I want the cell to show
the $45.00.

Thank you