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.