Hi sarahjean,
Welcome to Community. QuickBooks Online makes it easy to fine tune your sales tax filings, when you begin to prepare your return. Although you can enter a note in the memo section, there isn't an option to add a class at this time. If you would like to see this option in future updates, please don't hesitate to submit a suggestion to our Development Team by going to your Settings ⚙, then select Feedback. Customer recommendations are greatly appreciated in assisting us with improving your overall customer experience in QuickBooks Online.
If you have any other questions, feel free to reach out. We would be glad to help!