Your state should have a a form for tax exemption to submit to vendors, however educational use is not a reason approved in all states.
If trying to get ahold of a company, like Walmart, the fastest you will get a response is by contacting them Via email.
I think even when you die the government expects you to pay taxes
you should be able to get a form from customer service
From tax exemption for purchases?
Thanks! Your answer is awaiting moderation.