Is there a Plugin for tax exempt to work with this version?

Hi
I recently upgraded to version 1.5.3 from the official procedure and my tax exempt plugin no longer works. I have customers who are tax exempt. Can someone please suggest something I can do? I am sorry if I have posted in the wrong area as this is the first time I have posted anything. Thanks for any info you can give.

Was the plugin the one available from:
http://www.zen-cart.com/downloads.php?do=file&id=405?
Also from what version did you upgrade, and in the upgrade process did you merge in/around the files modified by the plugin? Ie., was it part of the update process?

If the plugin is the one from above, then from the description of the most recent version provided there is action needed to merge the changes that were made to the base files in order to have the program work in ZC 1.5.3. Whatever files were provided to support an older version of ZC should not blindy replace the files of a newer/different version of ZC. Instead, the changes made to those files should be compared to a clean install of the same version so that those same changes could be carried over to a newer/different version.

Ideally, once those changes are identified then they could be packaged up with the old product and provided to the site so that the next individual does not have to perform as much work to obtain the same result.