Rounding issue - Amount including VAT-Amount

Hi everyone,

I am facing this issue in NAV 2009 R2.
I have a field fieldXXX in the sales invoice where the user enters the amount including VAT.
When posting the invoice, the following check is made:
If fieldXXX <> ("Amount Including VAT" - Amount) THEN ERROR('%1 is not equal to total of VAT on lines %2',fieldXXX ,("Amount Including VAT" - Amount) )
The error message shows : fieldXXX=12.63 and ("Amount Including VAT" - Amount) =12.627621
Has anyone faced this issue before? How to correct it?

Thanks in advance