Chris, In simple terms, a Round Robin (in this case a $5.00 round Robin) is where I send 20 $5.00 chips to the first person on the list that wants to participate in a trade. That person just picks and chooses what he want and substitutes the same number of chips so that the package always has 20 chips (or whatever it was started with) and sends it out to the next person on the list.
This continues until all the people on the list has had a chance to pick and choose. It then comes back to the originator.