Hi,
No one else reported issues with PayPal with the "round prices during calculations" setting turned on.
So first, we would that you make sure that this option is activated and that you have the latest version of HikaShop.
If that's the case, we need a really precise picture of an example:
- a screenshot of the order details of an order with the problem
- a screenshot of the settings of the product in the order, of the settings of the coupon if any, of the shipping method if any, of the tax rule used if any.
- a screenshot of the payment details in PayPal
- a link to the product page so that we can reproduce the problem on the website.