Service billing and sales taxes

Currently, I do revenue recognition between two business units for materials that are issued out of one bu and "billed" to another. In this case the bu holding the inventory has paid sales tax on the item. The bu that is receiving the inventory is non taxable and right now we do a journal entry to "strip out" the sales tax prior to running service billing. The net effect is a transfer of inventory without the sales tax.

Can anyone tell me if there is a way to automate this process and how to go about it?