Hello @dburkhart1697,
As of the moment, there isn't an integrated way to assign a sales tax code to your customers based on location all at once. With this, Let's consider manually checking each of your customer's profiles, one at a time, so you can assign the sales tax code accordingly.
Also here's a reference with a compilation of articles you can use while working with us: Pay and manage sales tax in QuickBooks Online.
Keep me updated in the comments if you have any other questions aside from your customer's sales tax codes or anything with QuickBooks, I'll be here to lend a hand