I have not made any personal transactions within the deep web of the internet but i have read that it basically bitcoin and ethereum that are mostly used. But making transactions within the deep web is risky and i would advise you stay away from them before you lose your cryptocurrencies to some scammers.
Its speculative that is why it is never suggested to have some transaction in deep web because you can't easily say people's true intention, it is the reason why some people ended up feeling remorse after making transaction within deep web because of losing their funds and assets. I'm actually curious about what is going on there but there is something about it thats makes me afraid maybe the thoughts and opinions of other people towards it. Well as far as I know they are usually using bitcoin.