[Mad Dawgg]

"The answer is a national law setting a reasonable standard to require significant internet sellers to collect state sales taxes."

Ahhh, OK but a Law won't cut it. You must Amend the Constitution to do such.

[CharlesWayneCT]

Actually, you don’t. A national law providing for sales tax to be paid to states for purchases made across state borders would fall directly (and rightfully) within the Commerce Clause of the constitution.

The reason there is no collection of taxes now is that Congress has never passed a law authorizing it.