If non-blank, enables automatic addition of sales tax based on the order
form. The value is a comma-separated list of the field names (as placed in
order.html), in priority order, which should be used to look up sales tax
percentage in the salestax.asc database. This database is not supplied with
MiniVend -- it is typically received from a third party by quarterly or
monthly subscription.
SalesTax zip,state