Coming from a philosophical standpoint luck doesn't exist. When you get "lucky" it isn't an outside force that is rewarding you for helping a grandma crossing the street, it is just a concept we came up with to give reason behind things that seemingly shouldn't happen.
From a spiritual/religious standpoint it is the opposite. Luck could be your god(s) rewarding you for good behavior, or just making you lucky for no reason but to have fun. People tend to believe in luck as some outside force due to religious or spiritual beliefs.
I Think It should be 10. Cause If Something Is Not 5 or higher it can't be Rounded to the next number. since 3 is a low number it'd be 0 which means it would probably stay as 10