Rounding Issue with Pricing Conditions

Currently we have in place a pricing hierchery that consists of two pricing conditions. ZP for base price and ZD for a +-differential. Both conditions begin with 00. ZP00. ZP01, ZP03, ZP04. If a ZP01 exists it overrides a ZP00. If a ZP03 exists it overrides ZP00,ZP01, etc. So basically the higher the number means it overrides anything underneath it. The ZD conditions are setup exactly the same way. I am currently running into a round issue. We settle all transactions in USD however the manual and differentials are often based on prices that go out more than 2 decimal places. SAP is treating the calculation for the ZP and ZD as two separate calculations. It rounds each of them and then combines for a total price. So if the base price ZP02 is $2.245 multiplied by quantity 3,999 = $8,977.755 which it rounds to $8,977.76 and the differential ZD02 is $.0235 this = $93.9765 which it rounds to $93.98 for a total price of $9,071.74. However if you add the ZD02 + the ZD02 you get a total unit price of $2.2685. This multiplied times the quantity 3,999 = $9,071.731 which is correct. But because SAP does each calc separately the price comes out to $9,071.74 or off 1CT. I have seen various solutions on how to fix this from user exits to creating additional conditions that takes both ZP and ZD conditions and calculates them as one but I was hoping someone had come up with something better? Or if there was a preferred method?