Is it possible to associate the taxes in the POS (ERP 7.0) module with a user, rather then by a per product basis?

There was one way that I thought up, by using the Special Computation - Applicable Code (if type=code) section in the taxes and checking who the user is, and based on that enabling or disabling the tax. (Rather then checking for the user in Tax Type as that won't separate the taxes in the invoice)

Is this the best way of doing it? If so, how do you reference the current user in the python code? (an example would be preferred) Otherwise, how else would you be able to do it?