But the fees continue to build up no matter what 
the sender sends, as you pointed out, so is there 
really a point to adding this function to 
recalculate the fees? You can just as well input 
the total (payment and money to cover for fees) 
into the calculator and get the new total, but 
that doesn't solve the issue of how to have the 
buyer pay for all the fees by using Paypal alone, 
with the exception of minimal increase when the 
total is small.

---Trebuchet