for osCommerce Online Merchant v2.2

This contribution replaces the previous PayPal_Shopping_Cart contribution enabling the store owner to choose whether aggregate the total amount of the shopping cart to prior to passing it to PayPal (as Buy Now option), alternatively they can choose to pass the shopping carts invidually to PayPal. In either case this contribution fully supports PayPal's Instant Payment Notification (IPN) program, which automatically updates the orders table when it receives a vaild PayPal notification or when if indeed the customer clicks continue and returns back to the site after making their purchase.