Try doing a small sharp exhale while squinting your eyes and shaking your head side-to-side once or twice. (Kind of like what you would do if you just walked through a swarm of gnats and you think one might have gotten in your nose.)

If you are a full-body sneezer, the dog might think that something bigger is going on when you sneeze. What I described above is much more subtle, and easier to control/adjust to communicate with the dog, without startling or exciting it.