Questions about rounding taxes after the decimal point

Questions about rounding taxes after the decimal point

Hello.
I have a question about customizing tax rates for Zoho CRM.

I can't find a place to set rounding after the decimal point.

Currently, it is displayed as rounded up or rounded, but the required rounding is rounded down.

Example)
Subtotal: 3620
Tax: 8%
Total: 3909

Please tell me the setting method.

Also, if there is no standard setting, please tell me how to set it with a custom function.