Also from the listing:
Currently goHastings only charges sales tax in states where we have a physical presence. Sales taxes are calculated during the ordering process and will show tax charged for the delivery destination, based on current tax rates. Shipping charges may also be subject to tax in certain states.
They are a brick and mortar store located throughout the country and therefore are required to collect sales tax for multiple states.
LC
"Only two things are infinite, the universe and human stupidity, and
I'm not sure about the former." - Albert Einstein