I agree wholeheartedly, and it is not limited to "project" (as I don't have/use that and it still happens on every invoice).  I can't count the number of times I have had to correct invoices because tax was charged to an exempt customer.  How is any business with more than a handful of customers supposed to remember which are exempt, and what is the point of even entering it into the customer record if it doesn't override tax?  At the very least, there should be a flag/warning indicating that the customer is tax exempt so that the workaround can be used.

This is a fail in design.