Not sure if this is what you are asking but paper wallets aka bitcoin cheques work great.
Make a few dozen and put 0.1 or 0.02 in them or whatever you need. When it comes to paying, just hand it over.
The shops are small shops most of them sell eating products which can be an arbitrary small cost, problems come when such small amounts are involved with paper wallets, if people want to eat from multiple stalls they'll have to carry dozens of paper wallets of fixed amounts.
Yup. Most people are quite used to that these days, but it can be a drag. An old android phone with no cell plan can also be a nice platform for a real online wallet. Those can sometimes be easier to use than paper and metal tokens of fixed amounts. Takes a bit more infrastructure though.