You may not be aware, but AvaTax (from Avalara) is a web based interface that virtually takes care of all of your sales taxes. It is completely integrated with Sage MAS 90, 200, and 500 ERP. You can post only taxable, only non-taxable, or all invoices to the program, and all sales tax rates are handled outside of your accounting software. For a small additional fee, the company will even file sales tax returns. It is completely worth looking at.