Joe_Web_Filter - 4:41 pm on Jun 3, 2013 (gmt 0) [edited by: lorax at 6:46 pm (utc) on Jun 3, 2013]
minicart.js is an opensource shopping cart used by Paypal. I have made very few changes and use it on my site. I use it for Google checkout and Paypal. You can tweak it to make the shipping work as you mentioned above or a simple script to add the shipping on a checkout page. I have many products on a lot of pages and only have to edit 1 or 2 files to make changes sitewide.
[edit reason] no sticky requests please [/edit]
[edited by: lorax at 6:46 pm (utc) on Jun 3, 2013]