Hi there, Impact9.
We'd like to take a closer look at this to determine why POS is not calculating the taxes for some of your sales transactions. I'd recommend reaching out to Chat Support Team for QuickBooks POS.
They can help you review everything in your account setup to make sure that all of the items and sales transactions are taxed. They can also help you change the transaction totals to make sure that you have an accurate transaction record. You can reach out to them through this link: QuickBooks Point of Sale.
Please take note that due to the ongoing pandemic, our phone and chat support channels are only open between 6:00 AM to 6:00 PM from Monday-Friday, and from 6:00 AM to 3:00 PM on Saturday. Here's a quick guide for more details: Support hours and types.
Don't hesitate to reach out to us again if you need anything else.