Paypal modules return wrong price [rounding issue]

[Khaztech]

Prestashop 1.5.4.0 & 1.4.7.3

PayPal v3.5.7 and even older versions have the same problem.

 

I have read many many forums, but nothing is solved.

Here is the problem:

Prestashop and PayPal module count differently!!!

 

For instance I have 6 items for $8.75 each.

 

Prestashop counts:

$8.75 x 6 = $52.50

Then we add 13% Ontario TAX ==> $52.50 + 13%($6.825 => rounding to $6.83) = $59.33

 

PayPal counts: (And it's WRONG)

$8.75 + 13% Ontario TAX ($1.1375 => rounding to $1.14) = $9.89

$9.89 x 6 = $59.34

For some reason PayPal module adds and rounds a TAX for each product and this leds us to the problem

 

As the result we get a message: Warning: $59.33 paid instead of $59.34 !

 

Clients are complaining that we are cheating them, because they pay more then on Prestashop's invoices.

We also tried to change the algorithm in the prestashop, so the prestashop counts the same as PayPal, but we cannot figure out how to change the algorithm for invoices.

 

We also installed PayPal USA, Canada Ver. 1.2.1, but it is even not showing at the checkout and it is not working with the old version of Prestashop..

 

Please advise...