Large discount chain here. The majority of our transactions are in cash, as our customer base is notoriously under-served by banks.
Cash mainly slows down self-service checkout turnover (customers have to insert one bill or coin at a time); a semi-decent cashier at a normal checkout is quick at accepting cash and making change (with maybe a slight delay when cashiers need to break open stubborn coin rolls). Cash is still faster than check, and often on a par with most credit/debit users who are slow as molasses on following prompts on the terminals they use. Probably the most time-intensive thing done now is dealing with baby formula checks, WIC, and coupons, which severely slow things down.
Our cash office typically has two employees on hand for 8-12 hours a day. Figure $160 to $480 in payroll for that service per day, giving varying hourly pay rates. Some of that time is in counting cash, but they also consolidate the counting-down and refilling tasks that normally would have to be done by individual cashiers and/or management in years before (and probably recouping hourly expenses with just this, given how many cashiers would have to be doing this). They handle nearly every monetary I/O in the store, including vendor accounts, vending machines, repair contractors, utilities, etc. Did the overnight manager call in a snow-plow service? They’re dealing with that. Nearly all of the cash procedures are semi-automated, so the bulk of their payroll goes into dealing with all the other stuff, so cash doesn’t cost much on the back end.
With operating our own ATMs, check cashing at any register, and financial services center, we recycle a lot of the cash that comes into our store, turning an additional profit on it without having to send it out of store and reducing the amount of armored car service needed. Much of the cash coming into the store per day goes right back out as check cashes, wire transfers, ATM withdrawals (all of which give a few dollars in profit each) and cash-back debit transactions and government check cashing (which are free for the customer). The biggest cost of supplying money to the store is probably in rolled change; few customers pay in coins, coins go out in nearly every cash transaction, so we still have to supplement our supplies with frequent coin deliveries.
Before all the financial services went into place, the “shrink” on cash through all losses (fraud, theft, miscounts, counterfeits, etc., plus cash-handling expenses) was about 3%, about on par with credit/debit transactions, and lower than checks (~5%). Now it’s closer to 1%, lower than credit/debit. Shrink on coupons, on the other hand is closer to 10%, sometimes far higher when big forgeries spread online before they’re caught.