I have an order and I cannot make up what procent Amazon is suing to calculate theTax for "FBA Pick $ Pack Fee"

ON the Transaction Details page amazon will show me these numbers

FBA Pick & Pack

Fee Base amount : -$6.12

Tax : -$0.73

If you are using all the HST available values nothing match , not even close

for 5% HST the tax will be 0.30

for 13% HST the tax will be 0.80

for 15% HST the tax will be 0.91

If you will calculate the procent based on the base amount and the tax charge the procent is 11.92%

Any thoughts will be appreciated .

Thank You

Titri Hobby