add percentage fee on total order amout

[[email protected]]

Hi,

I have a shop using paypal as payment gateway.
I currently charge a fixed transport fee to my customers, in addition to the order total.
I'd like to add a percentage fee to the total amount the customer is paying.

total amount sent to paypal = (total order + transport) * special percentage / 100

What would be the best way to do that? Custom extension? Hack in paypal module? Hack in prestashop? Simple admin config?

Many thanks for your answers

[[email protected]]

is what i'm asking actually possible?

[SpyrosT]

Take a look here and here.

[[email protected]]

hi, thanks a lot for your answer, you saved me days.
I think there is a bug in the module.

The number of items (quantity) sent tot paypal is always 800 + number of products ordered
So if I have 2 items in my cart, 802 items are sent to paypal. It gives a hudge amout in the paypal interface.

Does someone knows where this could come from?
In the paypal.php file of the module, at line 365, I can see this:

$products = $params['cart']->getProducts();

This line gets the content of the cart then $products is assigned to smarty => paypal form data.
This line belongs to function hookPayment($params)

A var_dump ($params['cart']) tells me that the quantity is 800.

Isnt $params['cart'] a prestashop variable? could this bug come from prestahop or is it the module?