Quick Java Script / AJAX Modification

We have a checkout page for a cart system that is in ASP Classic - using JavaScript to calculate the totals. We have a new install and they want to change from our current that determines shipping based on value to number of items in the order times set amount with a limit. I already have the ship amount calculated in the VB Script - but need to get it changed where the Java Script sets the totals and I don't have good luck with Java - so just want a Java expert to do this quick change - should take you less than 5 minutes. Please only bid if you can do ASAP - I am trying to finish this today. Thanks