Got a PayPal IPN file however needed to start charging 10% Tax for Australian customers, and I have a fraud checker in the file to check to make sure the price matches the actual amount, so people can't trick it and only pay $[url removed, login to view] and get the product.
Since then, the new code has allowed the +10% tax to work with the IPN code. However now I have introduced a coupon system and the PayPal IPN file is not working sometimes.. but only sometimes which I don't understand. It says invalid transaciton due to the amount being less than the amount on the website due to the coupon code reducing the price but the PayPal IPN doesn't know that there is a coupon being used and it's calling it invalid transaction. (It thinks someone is trying to do something fraud and pay less money but it's just the coupon lowering the price)
Need someone to amend the PayPal IPN fraud checking code to make it work with coupon codes