Hi Liqua,

There are sometimes that due to different rule in rounding by QuickBooks Online API the 1 cent is always left off.
The rounding precision for sales tax calculations is designed for 2 decimal place precision in QuickBooks Online. So when inputting numbers into the UI or the API, you need to take this rounding into account.
Rounding off is done per line. To have a better illustration on how this is done in the system, please refer on this article from Intuit Developer on how they are being calculated: https://help.developer.intuit.com/s/article/QBO-APIs-Tax-Rounding-off-logic-in-QuickBooks-Online

Hope this answers your questions. Feel free to reach out again if you have any other questions.