I use the Paypal shopping cart for my small business website.  For that last few years I have had a flat fee set up for shipping based on dollars spent.  When they buy a product, the shipping is automatically added in based on sales price.  Looks like this:


What I want to do is incorporate the ability of the buyer to enter his/her zip code and have postage calculated from that - like you see with many sites, and Ebay.

Can it even be done using the basic Paypal shopping cart system?  Thanks.