The St Helens number nine appeared in front of the Rugby Football League’s independent disciplinary panel charged with making dangerous contact with Catalan Dragons forward Olivier Elima during his side’s 42-0 Super League defeat in Perpignan last Saturday.
Roby declined the chance to submit an early-guilty plea to the grade B offence and, after being found guilty, was given a £300 fine.
It means Roby will be free to play against Castleford in Sunday’s top-four clash at Langtree Park but his Saints team-mate Alex Walmsley will miss that game after being given a one-match ban after admitting a grade one offence of striking during Saturday’s game.
Walmsley and Catalan Dragons hooker Eloi Pelissier were both sin-binned after coming to blows and the latter was also handed a one-match ban, which will force him to miss the Dragons’ home game against Hull on Saturday.