Cart total not adding up correctly (subsequent PayPal payment error message)

[bocc123]

For the past two weeks, my system has committed several errors when adding up the total of some customers' shopping carts. The total amount is always off by 1,2, or 3 cents (Norwegian øre), which is expressed in the 2^nd decimal place. For example, when you add up all the items and shipping, the cart total should be 200,71 instead of 200,72. I have attached a screenshot of this particular order illustrating the problem.  

 

This addition error causes PayPal to report a “payment error” status to the back office (because PayPal’s cart summary adds up all cart items, comes up with a slightly different amount, and detects the discrepancy between its calculation and my site’s cart summary). Consequently, the back office sends a payment error email to the customer. This occurs even though PayPal always successfully processes the transaction and transfers the money from the customer’s account to mine.

 

Why can’t the system add up the total amount correctly? This is causing a great deal of frustration and confusion among my customers. I would appreciate any help here.

[saverio.cannilla]

There is a similar discussion here: https://www.prestashop.com/forums/topic/461977-paypal-charges-different-amount-than-the-order-value/

In a nutshell, the issue is that your cart and the paypal module are rounding the prices in a different way; depending on what is the correct\wanted rounding method, the solution can be as simple as changing the rounding settings in "Preferences > General" (set it to "round each article" in order to match the PayPal behaviour) or could require to modify some PHP files in the PayPal module.

[bocc123]

Yes, this seems to have fixed the problem, as I have not had any more errors in the past several weeks. Thank you kindly for your help.

[saverio.cannilla]

You're welcome.