Our shop has had payroll deduction for quite some time...long before I became manager, so I can't really say how much our business increased because of payroll deduction. However, I know our business would be greatly impacted if we did not offer payroll deduction....as our payroll deduction averages between 50% to 65% of our total sales.
It is set up with a $200 limit. If the Associate owes $100 or less, then $15 is deducted from each pay period. If they owe between $100 and $200, then $20 per pay period is deducted until they reach then $100 level. There is no minimum deduction, as we just swipe their identification badge, and all puchases are automatically transmitted to Payroll. We have Associates who use their badge for a candy bar purchase, because many of them don't carry cash.
We are paid every two weeks. I really wish that more could be deducted per pay period, because it takes us slightly more than 3 months to collect $100. But those parameters were in place prior to me.