The issue of probable cause would be interesting. Perhaps a Maryland jury would agree that it was suspicious that someone would try to pay for something with two-dollar bills and he would get nothing.
If it had been 114 one-dollar bills, non-issue. Store takes the money and moves on. The probable cause test here has to be to the police that detained him. I assume the probable cause test is subjective, so if the cop is ignorant in matters of currency, and is honestly fooled into belief he has a perp passing counterfeit currency, then he has probable cause. A belief based on a mistake, to be sure.
"The issue of probable cause would be interesting"
There is not sufficient probably cause here. The officer is so deficient he should be terminated along with all those superior to him on duty that day.
This will never go to trial.
It will be worth several hundred thousand dollar to the Best Buy national office not to be painted in court and in the subsequent news coverage as idiotic, jack-booted thugs that have customers thrown in jail for using U.S legal tender.