It's a last resort, for sure, but we've already discussed it. As of right now, we're limited to one roll of each denomination ($17.50) by our bank, so the need may very well eventually arise, and that means that some of my collection might just end up as someone else's change.
Remember, the concept of supply and demand is still valid even for currency marked with an official denomination. You could think of that marking as the _minimum_ value of the currency, as guaranteed by the state.
I think everywhere else I've travelled, someone (or a machine) giving change will optimize it to the fewest coins. £3.85 would be £2, £1, 50p, 20p, 10p, 5p.
The only exception is something like a food stall that's set all their prices to multiples of €1 (I've seen this several times in Germany), they might keep plenty of €1 and €2 coins for change. If someone pays with smaller coins, they have no use for them and will give them as change.
Having lived in Japan, I was a big fan of larger denomination coins. In Japan, the smallest bill is worth about $10 USD, and they have coins worth about $1 and $5. Having a pocket full of change could actually get you something nice! I actually treated two of my friends to a night out at our local izakaya for ~$100 with 20 coins.
In an effort to promote the use of different coins and bills in the US, I would take all of the one dollar bills I accumulated over X amount of time, and I would buy $1 coins (Sacajaweas and Susan Bs) and $2 bills so that I could circulate them and try to get people accustomed to them.
I ran into three issueus:
1. Cashiers would give me the wrong change for the $2 bill. They usually treated it like a $1 bill, but at times I got change for a $20.
2. Cashiers would be mildly annoyed that there was not a slot in their register for $2 bills or $1 coins.
3. I actually had one subway worker (at the T in Cambridge) actually throw the coins back at me and yell at me and my friends that she wouldn’t take our “circus money” while pounding the plexiglass. We were all in business causal and (I hope) didn’t look like circus performers, so it was an odd reaction to say the least.
Anyway, I do all of my banking remotely now, so it’s harder to make exchanges like that, but I still do it sometimes.
I really wish my fellow Americans would embrace the use of larger coins and maybe even ditch the penny and maybe even the nickel.
They could make a $2 coin. It would fit in with other Western countries' highest-value circulating coins:
2 GBP = $2.53
2 AUD = $1.40
2 CAD = $1.47
20 DKK = $3.10
20 SEK = $2.20
20 NOK = $2.20
2 EUR = $2.29
50 CZK = $2.54
10 HKD = $1.29
2 NZD = $1.31
500JPY = $4.67
I would expect 50¢ and $1 coins to be especially popular with people running vending machines or other machines giving change. 50¢ coins means refilling it less frequently, and encouraging $1 coins means less trouble recognizing paper money.
I wondered how the coin mechanisms on pool tables work in the USA, since nowadays it's probably not unusual for the price to be more than $1 or $1.50 (depending whether the mechanism has 4 or 6 slots). In Europe they just take whatever mixture of coins is appropriate, an image search suggests in the USA one must buy metal tokens to feed the machine.
I remember trying to feed about $6 in quarters into a payphone in the USA, when there was some issue with travel insurance and we had to make a call to Britain. We couldn't put them in fast enough. Eventually, the cheap motel let us use their normal phone.
(The first two are still in widespread use in the UK, although I haven't seen them much in Denmark or Sweden. Here, they're more likely to have replaced the coin slot with a contactless card reader.)