Give and take

"That'll be £37 for the parts and £35 for the labour and I have to tell you that with VAT it comes to £84.71" said my voicemail.
"Why did he have to tell me" I thought as I went into the small office with the big counter.
"How are you?" he said reaching for the invoice.
"Not too bad" I replied fiddling with my wallet.
"That'll be £84.71" he said.
"So are we paying VAT now" I wondered aloud.
"Oh" he said quickly, "If you're paying cash" He wrote something on the bill. I counted out £75 in cash and put it on the counter.
"Seventy" he said, pointing to the piece of paper where he had written £70 cash and drawn a circle around it. He gave me £5 back.
I smiled.
"I haven't charged you for your keys yet" he said - withholding his grin until just after I started to look worried.
I thanked him and left.