How to show only 1 tax line for 1 invoice

Summary:

For our affiliate, VAT is fixed as 5% for all expense. We want to change the setting for tax line's appearance and calculation.

Content (please ensure you mask any confidential information):

Before, when we create 1 invoice from 1 PO with many lines, only 1 summary tax line appeared.

But recently, the configuration Owner tax option was changed, after that when we create 1 invoice from 1 PO with many lines, each line will has 1 tax line accordingly. It leads to the fact that total tax amount will change a little bit due to the decimal.

I want to ask where to change back this setting to show only 1 tax line for 1 invoice.