Parry rogues don't exist except for the bonus to AC. Actually I don't think I've ever seen anyone use parry
I'm not sure of the difficulty to implement, but I think it'd be very thematic to allow characters with sneak attack to trigger it when they riposte a PC, essentially representing a canny feint followed up by a cruel strike when the opponent's guard is down.
Pretty sure this is impossible currently until the magical point in the future when the community patch comes out.