Paying state sales tax on items bought from an out of state
supplier and shipped into the state is a law that doesn't seem to
be enforced and with which the compliance rate seems to approach
zero.
If you use a site such as PriceGrabber (
www.pricegrabber.com) you
can put in your zip code and tax will be calculated for your state
of residence and if the merchant has a same-state presence.
I'm in California so I have to pay sales tax if I order from
NewEgg. If I order from B&H in New York, I don't.
I don't even know if CA has passed an internet sales tax bill as
have some states. If they have then I would imagine that there is
some provision to declare those purchases when filling out the
state income tax forms. (Don't remember seeing anything there the
last time I did my taxes.)