SAUGUS – Police are investigating a robbery at the Sizzle Tanning Salon on Lincoln Avenue that occurred shortly before 9 p.m. Sunday.A man about 5-foot-10 wearing a dark blue sweatshirt that covered his face walked into the salon at 302 Lincoln Ave. demanding cash, police said. It was unclear if a weapon was shown.The clerk gave the suspect an undisclosed amount of cash from the register and a cell phone, police said.No arrests were made Sunday.Police plan to view a surveillance tape that recorded the incident.- Dan O’Brien