this one is too complicated for my brain, so I need help... I'll do my best
to explain:

I have 4 cells (A1, A2, A3, A4)

A1 is a total dollar amount of a small section of a group of amounts

A2 is a grand total dollar amount of the entire sheet before any percentage
discounts are applied.

A3 is a percentage of discount that will be applied to A2.

A4 is a calculation resulting in 2% of A2 (A2*.02)

A5 is the total after all discounts are applied.

So here's the rub:
I need to subtract A4 from A5 only if A1 is greater than or equal to A4.