Hi there,
Welcome to the Community. QuickBooks offers a flexible tax module that simplifies the way you manage your taxes. I'll be happy to share info and steer you in the right direction.
In order for the program to calculate the taxes correctly, it's important to make sure you've set up the taxes appropriately. I encourage you to check out this article here that shows you how to set up sales tax. The program also makes it easy for you to file your sales tax. Here's a helpful article that shows you how to: File sales tax in QuickBooks Online.
You're welcome to ask other questions. I'm here to steer you in the right direction.