You shouldn’t have to pay sales tax anyway. You are in a different state than they are and they can’t charge sales tax across state lines.
So, the only people who pay sales tax to me (if they buy something directly through my store) are people in Minnesota. Everyone else doesn’t get charged sales tax. It should be the same way for Windstones. They only should charge sales tax to buyers in California now, and Oregon later (unless they don’t have a sales tax).