I'm reminded of a salutary tale. Back in the 1990,s we were selling Kitchen appliances, with several branches throughout the midlands, all in small factory units, direct to the pubic.
One local council tried everything to stop us, and after a particularly nasty war of attrition, they offered us a plum high street location, on silly terms.
It transpired, that the previous occupant who had been there for 23 years, and also sold brown & white goods, was well known for offering discounts for cash.
One day, an attractive lady appeared in the shop, interested in a cooker, and the salesman (Owner) offered to knock the VAT off.
The Owner was promptly arrested, got 3 years, business busted, lost home, wife etc....... How the mighty fall!
Needless to say, we always scrupulously paid our VAT in full, and despite the many approaches from customers to "knock the VAT off" and the retelling of the above tale, everyone to a man, said in protest and surprise, "But I don't work for HMRC". No, I would reply, and "neither did the attractive lady.".............