Matthews, who was not penalized, was fined as a first-time offender because his 2013 fine, which also was for roughing Foles, then a member of the Philadelphia Eagles, was rescinded upon appeal.
Former NFL head of officiating Mike Pereira said during the game that Matthews should have been penalized for the hit because it came against a defenseless player and with the crown of the helmet. Rams coach Jeff Fisher also said he felt there should have been a penalty called on the play.
Matthews said earlier this week that a fine wouldn't cause him to alter the way he plays.
"You play hard," Matthews said. "I play hard. What happens is what happens. I don't think anybody in this league, hopefully, intentionally goes out there to break the rules. You know, when you play hard, you have no regrets. That's how I play, whether it's a face mask or a low hit on the quarterback. I don't think anybody intentionally, especially myself, goes out there and tries to inflict illegal hits or pain or whatever you like to call it. It's just a byproduct of playing hard, I believe."
Matthews has also been fined in the past for hits on 49ers quarterback Colin Kaepernick and Seahawks quarterback Russell Wilson, but neither was for roughing the passer. The fine against Kaepernick was for a late hit out of bounds. The hit against Wilson, which was for an illegal blindside block during an interception return in the NFC Championship Game last season, cost him $22,050.