@elb It's a National Cash Register Model 11-EN made in the early 1950s. NCR was better known for their ornate cash registers, but they also made electromechanical adding machines like this one. They apparently were also involved in manufacturing electromechanical Bombe computers during WWII to crack Enigma.
@kyle I grew up near Dayton, OH -- there's tons of NCR stuff near there, they were founded and then headquartered in Dayton for many, many years.