Hello there, marcbou.
I tried to replicate the scenario in my QBO, and I was able to get $55.11 QST @9.975% of the invoice. The import process might be affecting the round off that’s why you’re $55.12
To avoid reconciliation problems, I’d recommend editing the tax calculation manually to match the amount to the other system. Just open the invoice and override the amount on the box next to QST @ 9.975% on 552,50.
Please don’t feel hesitant to drop by again if you have other questions about QuickBooks.