Cashiers are generally regarded as sort of rain men when it comes to figuring out the exact currency exchange between gold coins and current country currency.
In the morning they check the price of gold per ounce. This sets their base price for their shift. Hopefully, the price of gold goes up during the day and the store nets a little more profit. During the transaction, they hold the coin and determine the weight. (I should mention that they are highly trained to determine the weight of nearly any object under one pound they hold. It takes months of precision training, but they can get the weight of a feather or a gold coin to .0000001 oz by the time they are ready to serve customers.) Once he (and only men do this work) determines the weight of the coin, he makes a mental calculation of the conversion price of the gold coin’s value in current country currency. Mind you, all of this happens instantaneously, almost imperceptible to naked eye of the customer. He then will apply the value of your gold coins in current country currency and complete your transaction.
How do I know this? So, I was a precocious child, always holding objects and telling my mother their weight. (I should mention that I wasn’t vaccinated, since vaccinations have heavy metals in them and this throws off the body’s innate weighing ability.) She thought I was just playing until one day I picked up one of her gold earrings and said “this is 2.305 oz, mommy!” Astonished, she weighed the erring and I was 100% correct. Amazed at my skill, she immediately enrolled me in cashier school to foster my god-given weighing skills.
Sadly, when I became a teenager, I was showing off for friends at the local mall, weighing any object they put in my hands while I was blindfolded. They put cups, marbles … anything in my hands. Then someone handed me a knife to weigh. I thought it was a rod and I clasped my hand around it, severely cutting my left hand! I was rushed to the hospital but the cut was too deep. The wound damaged my nerves and I could never weigh another thing again.
So, to end this story, yes, this absolutely happened because I was once one of these magical cashiers.