You may be a company that sells products that are taxable for some customers and tax exempt for others. Research the tax status of the products or services that you offer and understand clearly which purchases are tax exempt. As a vendor, you charge sales tax to your customers unless they provide a sales tax exemption certificate.
Note all of the customers which issue purchase orders with sales tax and compare them to your state’s tax exemption list. Those who are being taxed that may be overpaying would appreciate your notifying them that other similar buyers are tax exempt. Forward the exemption list for your state to those customers for them to decide for themselves. They will appreciate you saving them sales tax not applicable to their purchases.
Make sure your sales people are trained about the tax status of your products or services. They should be the good guys notifying your customers. If anyone else in your organization notifies the customers, it robs the ability of the sales person to help the customer, something you want the customer to remember in the future.