The bajillion-jurisdictions problem can be solved on an aggregate basis.
Charge everyone $100 inclusive-of-taxes. Keep $93.50 of that from a customer in Phoenix, $92.75 from a customer in Los Angeles, and all $100 from a customer in Oregon. If you have approximate knowledge of how your demand breaks down, you could come up with an all-inclusive price that produces the average bottom-line revenue you want.
You seem to be hand-waving away the accounting part and the fact that the subtotals for the same goods will be different for users in different cities.
Charge everyone $100 inclusive-of-taxes. Keep $93.50 of that from a customer in Phoenix, $92.75 from a customer in Los Angeles, and all $100 from a customer in Oregon. If you have approximate knowledge of how your demand breaks down, you could come up with an all-inclusive price that produces the average bottom-line revenue you want.