Tax on freight when selling directly to consumer

I have a client that is starting to sell products directly to consumers.  They haven't needed to charge tax on freight until now, and it is not something they will need to do for every sale.  I've created a freight item, and have used fulfillment sets for accounting for the tax and for invoicing it correctly.  I'm curious to know what are common ways of dealing with tax on freight when selling directly to the consumer.