How can i add my sales tax report to the dashboard?

Welcome to the Community, @diana18.

At this time, there's not a way to customize to show certain content on your Dashboard in your QuickBooks Online. I'm going to submit feedback to our Product Development Team about allowing a feature that will allow this to happen. You can visit our Blog to see new features and upcoming updates to our Products.

Let me know if you have any additional questions. I'll be here to help you. Have a nice day!