Tax calculation error on expense reports

Hi! If somebody can help me resolve that problem, it would be greatly appreciated. I'm working for a Canadian company and we have people expensing in Quebec province (CAQC). I noticed last week that the calculation of GST/PST on expense reports doesn't calculate correctly. Even though I maintained right tax percentage rate on FTXP for ''T1'' Tax code; ''CAQC'' Jurisdiction code, SAP doesn't consider them. It's always a litlle bit off. Right now, we are not asking the right deduction to the government.

Every tax code are created with "V" tax type. The calculation level is from "100 to 110" for Base Amount. We duplicated the Flat Tax on Employee section and created Z condition type based on populated SAP condition type (JC1T and JC2T). We have ZC1T at 3.846% and ZC2T at 8.257%.

Here's an example of what we get for an expense report.

Person X : 100.00 CAD

Expense : 88.49 CAD

GST (ZC1T) 3.54 CAD

PST (ZC2T) 7.97 CAD

If you have any clue that could explain that situation, I'd be grateful.

Thanks in advance.