Modify PHP Script Integrate with Paypal API

I have a Paypal php order script. It sends the payment info to Paypal. Paypal then sends the order info to my [login to view URL] script on my server which is my Paypal ipn listener. [login to view URL] sends the order info to [login to view URL] which triggers a commission in my affiliate script Everything works except I must hard code the total order amount of the sale into [login to view URL] This is the part of the code I need modified: #$cashflow = $amount; # replace amount with the variable contiaining the final purchase price if($amount) { $cashflow = $amount; } else { $cashflow = '67.77'; } $cashflow =~ s/[^0-9\.]//g; I have to put the exact amount of the $cashflow (total amount of sale) in order for the process to work. (in this case it is 67.77) I need to put a variable in there that changes with the different sales amounts. I will be having products with different prices. If I just had a product with on price I would be fine but I need to put a variable into $cashflow=' ';} that changes with each order amount. I need to know what variable to use to send the total payment amount from [login to view URL] to [login to view URL] so I do not have to hard code the exact amount into [login to view URL] I can set up ftp log ins for you. I need somebody familar with php and with paypal api. Thank you