HST on purchases

We are a charity registered in Canada.  As such we receive a portion of the HST that we pay on purchases refunded back.  The amount of the HST net of this rebate is recorded as part of the expense.  The transaction is recorded as two items - the first is the amount of the purchase without tax and the second is the net HST amount.  Is there a way to have the two amounts added together and recorded as a single expense amount?