[mikeash]

Seems to be the shipping address.

[davidgh]

Some state sales tax rates are destination-based and others are origin-based. Since sales tax was not designed to consider the internet, things get complicated fast.

[SubiculumCode]

Then is shipping to an intermediary low-tax address (as a service) followed by a separate shipping event to your home an illegal circumvention?

[snuxoll]

Yes, you owe use tax to your home state on the difference in sales tax.