According to Jack Reacher, Charlie killed 4 people with a sniper rifle and before doing it he drops a penny at a parking ticket machine, so the cops got the finger print which matches the Barr's. How is this possible?
The money belonged to Barr so it had his fingerprints on it.
The gun was also Barr's as was the van. The whole point of Charlie's actions were to frame Barr for the killing. He had befriended Barr to get close to him and was close enough to be able to drug him and take the various pieces of property away from Barr's house and to return them with incriminating evidence without Barr realising he'd been set up.
If I remember correctly the movie shows a jar filled with coins on Barr's desk. Presumably Charlie just took one of these to leave that final piece of incriminating evidence in the multi-story car park.