Sales tax is imposed on the buyer, not you.
So my first thought is that you need to amend your prior tax returns. In your example (I'm from MN, so I now those numbers are not actually accurate), rather than reporting $100 of income, you should be reporting $90.91 of income ($90.91 +10% = $100). But then in turn, the sales tax should be based on $90.91, not $100.
