Even if the national site has a minimum threshold, it's just that -- the minimum. The chapters can set their standards higher.
If the organization has graduate membership, you may consider that. But if your GPA is lower than what they want, there's really no "should I even try" -- sorry.
A Master's degree program (assuming that you get in) will not coddle you and will not accept *any* excuses (adjustment, family issues, tough classes, heavy class load.) In my program, if memory serves, at least a 3.0 average was required or you were out the door. I had to produce 60 pages of text within my first month of grad school. My program didn't play around. You either got the job accomplished or you were GONE.
You can certainly always try with the sorority of your choice. The worst that will happen is that you are rejected. But if you truly want or need to go to grad school, I would put my focus on academics instead. Also consider that the intensity of grad school makes it an ideal place for forming bonds with your cohort.