It cant be done, you as a BTC user supposed already know that this couldnt be done because each transaction is dependant and no one would know if the transaction is coming from the country or not
The only way they could benefit themselves with BTC would be by tax-ting every BTC/FIAT exchange, huge tax will then discourage most people to exchange their BTC
Unfortunately this deosnt stand for a developing country where there are alot of poor people living on the street and also there is alot of taxes, eventually when you buy something of a mini store there will be tax apply to your groceries as well