Geo-based tax exemptions in OFBiz?

[Jonathon -- Improov]

Say I have a TaxAuthority for GeoId "CHN" (China). And some provinces in China are tax-exempt 
where this TaxAuthority is concerned.

Is there a way to create an "area-based" tax exemption in OFBiz? Or must I create a TaxAuthority 
for every province instead?

Jonathon