[ic] Negative Tax - bug?

[Dan Bergan]

I'm having an issue where negative sales tax amounts are computed.
The issue arises when there is a discount on the entire order, and the
products in the cart are nontaxable.

A detailed description and potential solution is here:
http://www.icdevgroup.org/pipermail/interchange-users/2007-May/047410.html

This issue was also found here (with no resolutions):
http://www.icdevgroup.org/pipermail/interchange-users/2005-September/043923.html

Is this a bug?  It doesn't seem like a negative sales tax should be valid.

Thanks -
Dan Bergan