Round robin is a side effect of the people spamming keys with commas to get past CDs. I feel that if we used /casts to get around cooldowns, they would break that also. Pretty much everytime we find a way to get around CDs, they find a way to break it. I wish there was a way in-game to have a blank step in castsequces that wouldn't work more than like 3-4 times, so long strings of them wouldn't work, but not yet.

So you have to find spells/actions that don't do anything to use as fillers. I tried and it became really hard, since some actions you do on others and some you do on yourself, some only work with pets out and some use resources that kinda hinder you.
Locks: use fel armor as a buffer, doesn't take a target, but probably doesn't like it if you try to cast on enemies. Their curses aren't so bad to use and don't need facing, but that eats up GCDs and mana.
DKs: use any pressence, but doesn't like it if you are already in it and won't cast on enemies. If you use a disease, you either have to be in melee and/or it uses a rune to do it.
Hunters: use an aspect, but won't cast on enemies and will turn it off if used again (even number of times).
Pallies: don't have simple one to use, a cleanse on yourself or teammate won't work on an enemy and is kinda expensive. Might be able to use an aura, but probably turns it off if you use it again.

So it was pretty much screwed in game. I have moved my round-robins outside the game into HotKeyNet. Look outside the game for round-robins that work well. Use in game stuff for simple things.