There is quite a huge difference in "Jackpot" and "Jackpots". The use of these two domains is really different. Jackpots.io will work as some kind of affiliate site or listing different jackpots and should be priced accordingly as well. Jackpot.io is a completely different story as is it way more brandable than jackpots.io

I don't want to sound like a downer, but there is no way that you will get 5BTC for the domain. Good luck! If I am not mistaken, jackpots.io is a hand-reg from a few years ago? I have seen it for sale for around $1k.