[ic] Don't charge shipping for certain items

[interchange-users@interchange.redhat.com (Michael Goldfarb)]

4.8.2
RedHat 7.2

I have looked all over the mailing lists and archives, but I cannot decide 
what is the best way to handle shipping cost calculations on a per item basis.

For example, I have one client that has a catalog that charges shipping 
based upon Total Price.  One of their "Items" is a Donation that people can 
make on the site.

Is there any way to somehow flag the value of the Donation to not count 
when the system calculates shipping based on the total cost of all of the 
items in the cart?

The closest thing that I have found so far is this message that was posted 
last year which gets me close and I could probably hack it from there.
http://interchange.redhat.com/pipermail/interchange-users/2001-March/005744.html

I was just wondering if anyone else has already dealt with this issue...

Any pointers are of course much appreciated.

- Michael