Hello pthiessen1,
Class tracking is a useful way to keep track of your various transactions. This internal labelling system allows you to add class to transactions and even some items so that you can run reports to see data in a certain way. Check out this article to learn more about this feature in QuickBooks Desktop: Set up and use class tracking
Because of the way class tracking in configured and its use as an internal tracking system, breaking it down on a bill or invoice in relation to sales tax isn't something that's available.
I recommend reviewing reports in the program and tweak them to see the information you're looking for. Look for reports where you can add a column for both the sales tax code and class, or that you can filter by either of these and see what you're able to produce. Here's an article with more about customizing reports: Customize reports in QuickBooks Desktop
Take care and see you next time!
