All the three are used, but the two "gg" gave are the most commonly used (I only use those for instance). Rarely people say "à tes souhaits" after the first time you sneeze, "à ta santé"after the second and "à tes amours" after the third (but it is not something you hear every month, or even year).

a votre sante

à tes souhaits à vos souhaits