I can't recall there ever being anything like that. I guess the way MERP handled criticals (note: it has been a long time since I played MERP, so this may not be entirely accurate) mimicked the idea to some extent, since the difference between criticals was just a modifier to a single table, meaning an A critical could never kill, while an E was always pretty bad.
If you wanted to mimic this in Rolemaster, I would roll all criticals on the 'C' chart, and just apply mods to the roll (e.g. A = -40, B = -20, C = 0, D = +20, E = +40).