We are already using your PayPal Express Checkout Plugin in several Shops.
I tried to test it in another shop, but I got the Error Message "Error. Your subtotal was changed. Old amount = 31,80, new amount = 31,76." after I tried to confirm the purchase in the paypal popup window after paypal registration.
I tried to purchase 12 items for 3.15 incl tax (total of 37.80 incl. tax).
This was shown in the NopCommerce Cart Page
In the paypal popup, they displayed the price per item without tax (2.65 each), then added the tax again. But this changed the order total by 4 cents.
Did you noticed this before? Is there a workaround or configuration available?