I have the invoice#3726 Subtotal" 75.84 " Tax " 15% " TAx is supposed be " 11.38 ", but it is showing 11.39 How it is possible?

Hello there, 

I know how important it is to ensure accurate tax calculation in your QuickBooks Online account. QuickBooks is designed with precision to ensure your numbers are generated correctly. I'd be happy to shed some light on this for you.

You may notice a penny difference in your transactions because the rounding precision for sales tax calculations is designed for 2 decimal places in QuickBooks Online. There's been an ongoing discussion about this in our Community forum, where some users have offered helpful insights. Take a look at that thread here: Tax Rounding.

I'd also encourage you to explore this article: Tax Rounding off logic in QuickBooks Online API. This goes through the tax rounding logic in QuickBooks Online from the development team.

We always value customer feedback. I recommend sending your thoughts and suggestions to the engineering team directly by clicking the Gear icon > Feedback. We're always looking for new ways to improve. 

If you have any other questions, let me know. 

Cheers!