State Sales Tax on a Purchase Order for a non-profit organization

We are a not for profit organization and did not expect to have to deal with sales tax.  However, in the state of North Carolina, state sales tax must be paid.  If you have a tax exempt certificate, you file for a refund quarterly.  Does this functionality exist in PeopleSoft so that a state sales tax can be entered on the PO so that when it arrives on the invoice it does not produce a match exception?  Is anyone using it?

We are also a non profit in California. We have the Buyer apply the sales tax flag on each PO line that is taxable, to auto add sales tax on top of the PO amount.