As far as I can recall, I am unaware of any supermarket chains that accept BTC as a payment method. Having been said, there are ways in which you could still use your BTC to pay in said stores.
There are numerous debit cards around that are either linked to Bitcoin wallets or that are able to be loaded using your BTC balance. The balance is then converted at the current exchange rate to a total in FIAT which is then spendable in store. Its not ideal but still better than nothing.
In the Philippines the famous 24 hours store here "7/11" is accepting BTC as a mode of payment, but no supermarkets. Individual merchants and some online stores are accepting BTC but as we can see the supermarkets are cautious enough because they are big companies so they can't just let BTC be a mode of payment without proper rules regarding this per country. But the is disrupting the market, we don't even know if wholesalers and retailers will last because as we can see the blockchain can direct this to manufactures. Remember the emerging project called INS. There will be so much change so I think its better for the supermarkets to consider cryptocurrencies before its too late.
Wow i lived around 3 years in the philippines an left recently and had no clue that 7/11 was accepting bitcoin. But it s also true that i wasnt living in Manila and the few times that i went there didnt pay attention
I think it's possible that in the future most cryptos will be accepted at supermarkets the same way they accept different different credit cards. The main issue noawadays with cryptos is the scarcity of use in everyday life but this may change soon and then the bubble talkers will all disappear