I found a terrific online resource to help you calculate taxes on your orders. Remember, taxes are charged based on the "ship to" address. Naturally the system does this for us when we place an order online. However, if someone is purchasing from your inventory or they're paying you with cash or a check, you need to calculate the tax appropriately.
Try it out. Just click this link and fill in the information and presto!
For your future reference, I have placed a link in the FEATURED LINK Section on the home page.