Did a search and found this site regarding sales tax refund in Canada:

http://www.nationaltaxrefund.com/eng/intro.htm

Louisiana has tax-free shopping for international visitors but the merchant has to participate in the program. I'm sure each state has their own program, if at all.

Come to Oregon....NO TAX! Its also illegal to pump your own gas! Could life be better?

I had never heard of this being possible, but did see that some of the bigger stores in NYC give foreigner's some sort of "pass" so they can make purchases without paying sales tax. They must show some type of documentation. I think Macy's and Bloomingdales do it -- check their websites.

Hope this helps...
Debi

Other than Louisiana, no other state gives international visitors a break or rebate on sales tax. But, like Oregon, Delaware and New Hampshire have no sales tax.

The pass at Macy's is NOT tax-free shopping, but a card, available to both domestic and international visitors, that permits a 11% discount on shopping.
www.macys.com/visitor

By law, stores can neither waive a sales tax on retail sales nor claim to pay it.

I've heard rumors that the long-time policy of refunding G.S.T. to non-Canadians is going to be phased out very soon. Look into that before worrying about how to apply for such refunds.

Well cripes, I just bought a coat at Macy's a couple of weeks ago. I did get a good sale discount but I wished I had known about the 11% discount. Thanks Paul Rabe, I will remember that in the future as the SF Macy's store gives that discount. I wonder if you have to reside out of state to get it though. I will sure check into it the details.

Thanks for all your replies - very helpful. What about tax on accommodation and car hire rental??
We will be arriving in San Francisco for 6 nights then fly on to UK, come back to Vancouver, drive down to San Fran and fly home to Australia from there. So any advice on taxes and buying a cell phone to use for both countries would be appreciated.

All of the taxes that you will encounter -- sales, rentals, accommodations -- are imposed locally or at the state level, not at the federal level, so also the tax rates and the rules for applying them are determined at each state level. It sounds like you need to know specifically about the policies in the states of California, Oregon, and Washington.

As with the British VAT tax, it's unlikely that you'll be eligible for exemption or credits on things you actually use in-country (meals, rentals, etc.) though apparently there's a possibility of a retail exemption.