A few years ago, I was volunteering at a local fair and wound up manning a local vineyard's sale stand. The pricing was very simple: A bottle of wine or grape juice was 20 (local currency, which amounts to ~$6), buy any 3 bottles and get a personalized mug and box. Vendors were supposed to give samples to anyone who walked through the stand and try to convince them to make the biggest purchase. Vendors would get 5% of each sale as "commission" (more like incentive), up to a maximum of 100 per day.
A couple in their twenties taste tested every sample we had and decided for 3 red wine bottles. They paid and everything was hassle free. I proceeded to give a sample to another person, and while I was in the middle of explaining prices, they return and the boyfriend, completely ignoring my potential customer, barks "Hey, so I already bought three bottles and you'll let me buy a juice bottle for 10" while extending a 10.
"All bottles are 20, and that's final", I answer while giving the new customer another sample. Boyfriend is not satisfied. "OK, so you want 20 and I want 10. Let's do that thing of meeting halfway and I'll pay ya 15", he says with a huge grin. Since the new customer was apparently in the middle of deciding whether he wanted or not to purchase anything, I turn my full attention to boyfriend.
"20 means 20."
"But I already purchased 3 bottles! What's the hurt in taking 5 off?"
"Some people got 12 bottles and they didn't get 5 off. No one is getting anything off."
"Alright, you're a tough one! I'll buy for 17,50 and that's that!"
"OK, now you're only missing 2,50."
"Seriously? You can't take 2,50 off?"
"I wouldn't take 5 cents off."
"Alright, man, no need to get snippy! 19! You can't deny 19!"
"For fuck's sake, if you're willing to pay 19, just pay 20", the new customer exasperatedly says while going away. Good, now I lost a sale. Girlfriend shakes her head and meekly says "Please, just pay". Boyfriend completely ignores both and asks for a manager. I call the senior volunteer, who was the closest to a manager the stand had. Boyfriend proceeds to berate me and say I wasn't being helpful and what's the hurt in taking just 1, JUST ONE off the price of 20. The senior volunteer thinks for a bit and says in a very serious tone.
"OK, sir, as a special exception, we can make it nineteen..."
Boyfriend has a shit-eating grin of victory plastered in his face.
"And ninety-nine cents. No lower than that."
I wish I had a picture of the look on boyfriend's face as he realized we would round up to 20 since our country hadn't used the 1-cent coin for a few years. Defeated, he wound up buying 3 more bottles to get an extra mug (?). His girlfriend was laughing at him the whole time.