Nonrecoverable Tax Account

We have accrure on receipt turned on.  When a purchase order is created, there is no tax on the PO (go to manage tax at PO level and tax is -0-).  When AP Invoice comes in and is matched to the PO, the non-recoverable tax piece is going to the Inventory Accrual Account.  As a result, this piece is never offset and their is this cumulative balance for nonrecoverable tax, in the accrual account.  Here are the entries we're seeing:

When PO is created:

Charge Account      DR  687.52

Accrual Account                                      CR  687.52

When Invoice comes in:

Accrual Account      DR  687.00

Freight                    DR  25.00