I can hold my sneezes in if I'm in a situation where sneezing would be awkward, for example in a meeting or if I'm at the cinema and a very tense/romantic/sensitive/etc. scene is going on. But mostly I just let them out since there's a point with them.

In that case, I think I sneeze quite loud. Not half as loud as my dad though, but he exaggerates it a lot. He'll scare anyone who's in the same building.

I also had a classmate, who sneezed so quietly it could barely be heard, but I don't think she tried to keep it in. She was like "chi! chi! chi!". It sounded so cute