[ryandrake]

Allowing gas stations to denominate their prices by the 10th of a cent has always struck me as a just an underhanded and extreme way to practice the "9.99" retail psychological trick. Why not allow retailers to price things 9.99999? Ridiculous.

[cwmma]

It's because technically the dollar is divided into Dimes, Cents, and Mil. (this is why dimes say 'One Dime' on them instead of 'Ten Cents'.

So while the mil isn't really used anywhere else that regular people see any more due to inflation, it is a valid division of the dollar and that's why they are able to get away with it.

[Aloisius]

> (this is why dimes say 'One Dime' on them instead of 'Ten Cents'.

No, it's purely stylistic. We tend to spell out denominations on coinage and "dime" is just the American spelling of disme, meaning a tenth.

The capped bust dime from 1809-1839 had "10 C." rather than "One Dime". Similarly, the capped bust quarter said "25 C." instead of the modern "Quarter Dollar", the half dollar said "50 C." rather than the later "Half Dollar" and the half dime said "5 C." rather than the later "Half Dime."

Most of the 18th century and early 19th century coinage, besides half pennies and pennies didn't have their denomination written on them at all.

[georgefrowny]

There is no such decipence division in the UK, but fuel is still sold with a vestigial .9 pence on the end. In fact, since the denomination is per litre, not gallon, the .9 is about 4 times more significant.

When the final calculation of XX.YYY litres * AAA.9 pence/litre is done, it's then rounded off to 1 pence.

Currency conversions are also frequently done with readers that aren't a round multiple of pence, even in official government tables: https://www.trade-tariff.service.gov.uk/exchange_rates/view/...

[munk-a]

I'd like to clarify that point a bit.

They're allowed to get away with it because of a dysfunctional lobbying driven government. Mils don't exist in the common knowledge and if any reasonable person looked at this they'd call it out. It is useful in accounting but a Mill has never been minted and the last half penny was minted in 1857. It has never been possible using issued physical legal tender in the US to pay a debt of $3.129

The Mill doesn't exist because of some archaic need - it's pure dysfunction and the utilization of it in gas prices is a practice that should and very easily could be made illegal.

[ryandrake]

Yes, the "Mill" discussion looks to be totally irrelevant. [1] and [2] seem to back up my claim that, at least in modern times, it's purely a "just-below pricing" psychological trick and has nothing to do with the Mill unit.

$4.999 looks a lot smaller than $5.00 to everyday people and it makes the gas company more money than $4.99. That's all there is to it.

1: https://www.cbsnews.com/minnesota/news/why-do-gas-prices-alw...

2. https://www.cnn.com/2022/06/14/energy/why-gas-prices-fractio...

[Fritatta]

Certain states have manufactured plastic mill tokens in the 1920s and 30s to aid in the payment of taxes: https://en.wikipedia.org/wiki/Sales_tax_token

[LadyCailin]

So do whatever they do with mils but for the penny too. They don’t nor have they ever minted a mil coin, so the procedure for this is already well established if this is correct.

[dimensional_dan]

Has a Mil ever been minted?

[munk-a]

It has not - and it's been more than 150 years since the last sub-cent denomination (the half penny) was minted.

[Fritatta]

Not by the US mint but they exist: https://en.wikipedia.org/wiki/Sales_tax_token

[AnimalMuppet]

Turns out the station charges you a round number of cents per gallon. Then there are federal taxes, which are, IIRC, 24.5 cents per gallon. And then there's state tax, which varies from state to state but seems to always be x.4 cents per gallon.

So I don't think it's just "evil retailer tricks".

[Wowfunhappy]

Actually, I'd say by all means, allow them to price things $9.99̅ so we can all agree it's equal to $10 and be done with it.

[patrickthebold]

of course 9.99...(repeating) is mathematically 10, so I have a hard time being against allowing that.