Authorities released surveillance pictures of the suspect, who they say entered the Citgo Gas Station mart on North Country Road just before 2 p.m. on March 9.
Once inside, he allegedly removed a cancer donation box from the counter that contained cash.
The suspect is described as a heavy-set white male in his 20s.
A $5,000 reward is being offered for information that leads to an arrest.
Anyone with information about this crime is asked to call anonymously to Crime Stoppers at 1-800-220-TIPS. All calls will be kept confidential.