COD Surcharge

Is there any way to add a surcharge to COD orders?

I am pretty inexperienced in php, so the following probably isnt saying much, but I looked into the cod.php file and from what i can tell that only affects how it appears in the list of payment options and how the cart processes the order on submit.

Any ideas?

Thanks

You should not modify cod directly but...

You could create your own payment extension that managed the method for calculating the surcharge.
In other words, the admin section for that extension would have data entry for
eg: a fixed amount to be defined if the surcharge is constant in all cases.
eg: a percentage amount to multiply the order total by if the surcharge is a percentage of the order

etc etc