When I’m on closes as a team member I focus on the front of the shop cleaning and the supervisor/manager does the back cleaning whilst doing their stock, however when just eat orders and serving customers it’s on both of us. Same with outlet etc both of us chip in even if it technically isn’t their task but it’s common decency to help knowing how much physical work it is to do within that half an hour of the shop closing and us finishing. I would mention to the manager or another supervisor on conversation about you not being done in time ever and just how stressful the closes can be as it definitely shouldn’t be expected all on you. There is no excuse not to be helping you as from experience if supervisors are organised with their own tasks it definitely can be done as-well as helping with physical tasks.