Allocate full payment amount checkbox or button

When I enter a customer payment, I would like to have a check box like the one for “Allocate payment amount” but for the full amount of the transaction.

I’m asking this because when I receive money over paypal, there are always paypal fees. So if the total is 250, I’ll receive maybe 245.
So I have to enter 245 in the Paid amount and then click on “allocated” in the row to re-enter 250 for the full allocated value.