“Many companies have a cash register in addition to the official cash register” | EUROtoday

“Cash payment only possible” – it’s not unusual to learn that in eating places or hairdressing salons. This doesn’t essentially point out tax evasion, says tax auditor Edo Diekmann. However, there are some indicators that ought to make clients skeptical.
https://www.welt.de/wirtschaft/plus249390326/Viele-Betriebe-haben-neben-der-offiziellen-Kasse-noch-eine-Bargeldkasse.html