Should I tell my mom if i found cigarettes in my sister's room?

I was looking for my ipod in my sisters room one day because i think she took it. And then i found snuff in her trash can. It was empty and it just had the container. Im only 13 and my sister is only 16. She and my mom have trust issues already. I was wondering if I should tell my mom. Would it make things better, or worse.