Darth-Mart was the Sith Order. You couldn't even be a Sith without first being a Darth-Mart employee. Most of the Sith left as soon as they were promoted to cashier or tagger, but many continued to work because they needed the money. However miserable the time they spent at Darth-Mart, where trainees were subjected to Force Lightning if they didn't follow code, it helped all the Sith in the long run because they used their pensions to do their sithly duties.