Tax problem

How/when is the state tax figured? I am setting up a cart for some one in Arizona, but I don't see the tax being added. When I go to paypal they add the Arizona state tax, but the shipping/billing address is Ohio. Can anyone enlighten me as to the answer?

You have to collect tax for any orders that are shipped to the state in which your business has a physical presence.  Otherwise, you do not have to collect taxes.

How to translate that to the vaguely-evil paypal, I do not know.

I live in California, how do I put the 8.25% tax so that item ship to CA are tax with that rate?