Having an ATM does not make a business an MSB. Only transacting business in the following way makes them an MSB:
Issuer/Seller/Redeemer of money orders or traveler's checks (over $1,000 per customer per day)
Money transmitter (any amount)
Check Cashing (over $1,000 per customer per day)
Dealer in foreign exchange
Provider/Seller of prepaid access (over $1,000 per customer per day)
This is sort of the basic guide; obviously if the customer is an agent for these above mentioned transactions (other than check-cashing), then they aren't required to register as an MSB. They would simply have to provide proof of agent status.
FWIW, my previous bank monitored businesses with ATMs as part of our "MSB" monitoring; they were kept as a separate type of business but it was a risk-based thing.