You need to quote me so I will know you replied. As far as know all research assistantship automatically covers tuition, although you should search the website of your program or ask the department.
Well this probably does not answer your question but two years ago I was offered MS admission from NYU even though I applied PhD. I opted not to go as I thought I would be impossible to live in NYC without funding. Two of my friends had the same MS admission. They went and all got some form of research assistantship.