The man was arrested on Tuesday 26th March and has subsequently been released on police bail.
Poilce would still like to hear from anyone who witnessed the incident on 24th March or who has any further information to come forward.
Detective Inspector Ash Wilson said: “A robbery of this kind is not a common occurrence in Retford and it appears the offender waited until the shop was about to close to strike.
“We think he may well have discarded the plastic tray he used to carry the cash in after the robbery.
Have you seen it? If so, call us.” He added: “We are making enquiries in the local area, including reviewing CCTV. Patrols have also been stepped up in the town centre to provide reassurance.”
If you saw anything suspicious in the area around the time of the robbery, or have any information, contact Notts Police on 101 or call Crimestoppers anonymously on 0800 555 111.