Yes and No. Any infection can be transmitted to others via close contact. If the sinusitis produces cough, sneezing, nasal discharge then those particles in that secretions get to your hands, the tissues or clothes used to cover or to their respiratory tract and they may get it. In general if there is no contact with those secretions through cough, sneezing, nasal discharge, saliva ( kisses), hands :no.
Sinus Infections. Generally, sinus infections are not contagious beyond the time period of one of the main causes, a recent viral infection. During the viral phase, the disease may be contagious. If allergies or irritants are the cause of the sinus infection, these are not contagious. So, yes and no.