Notice Jesus didn't say it is or is not lawful to pay taxes. That's because taxation to human rulers is a judgment of God to a rebellious people.
Discussion
I concede that he dodged the question of whether it was right/lawful, but he did very clearly instruct people pay the tax though.
Funnily enough, if the coins don't have the tax man's name on them (Ceasar, in this case), he made no statement on whether people should pay the tax or not.
So an interesting parallel could be drawn there if paying via bartering.