I've answered a similar question some time ago. But maybe let me rephrase it here.
The idea of a sufficient GPA for entering a graduate program is more of an applicant's subjective concept than a real requirement by the graduate schools. The schools have repeatedly spoken about their holistic admission process and that no single factor will guarantee admission/rejection. By looking at the applicants' profile in this forum in previous years, it is also easy to observe that there were always applicants with substandard scores who got admitted in top-tier universities. There were also applicants with high scores who failed to get admission everywhere. *cough*(personal story)*cough*. However, applicants' insecurity will demand the existence of a single factor under their control that provides a peace of mind in the stressful application process. This is not just about you, but also about all the applicants in this forum who need confirmation on their GPA or PGRE/GRE score.
Knowing that, it is not for us in this forum to answer what the sufficient GPA should be. I think none of us work in the admission committee and even if we do, there is no way that we can release such information publicly. Hence, it is more of a question of how high of a score would give you, the applicant, the security and confidence to continue with the remaining application procedures.
Such line of thought is just not healthy, I assure you that in the end, there will be no number in this framework that suffices beside a perfect score.