The shops could give out more of each products so that it could be rounded up to the nearest pound.
Such as:
Three little gem lettuces for £1
Two cucumber for £1
Three bunches of spring onions for £1
And so on...
This is better than having loose change on me all the time. Coins are a nuisance. No where to put them ans even your walets dont want coins as there aint a coin department in wallets anymore.
Indeed this was suggested to me about 30 years ago!
The objection then, as now, is people not wanting to buy more than they need.
Supermarkets want you to buy more than you need, 3 for 2 offers etc, some of which could be banned, but hey they have to keep prices down.
On the common items where people would spend less than a pound it would be possible (with a little ingenuity) to offer "any 2 for a £1" or "any 3 for £2" or whatever, not to sell items people don't want but just to get rid of something that is actually sexist against men. Women carry handbags and purses full of junk: we don't.
Sometimes I want to pay cash. I have a tiny coin bag I try to remember for coins given in change, then just tip those into the auto-checkout first next time. But I'd rather not carry it. A slim wallet fits in my jeans, is just one item, nowt to carry. I don't want a metrosexual bag.
In the EU I heard that every note is tracked. Maybe we don't have that here but I like to think we can still spend money without being snooped on.
Another reason is that bank statements are harder to read meaningfully when they are clogged up with tiny purchases, a coffee here, a bus fare there. OK, there's a way round that (use a different card for small purchases, another one for Amazon and so on) but it's a hassle.
Paper money gives you more control over your life in my opinion. You look in your wallet when buying a round or impulse purchase and see the difference compared to how much you came out with.