Our college counselor told us applying T5, weighted GPA should be at least 4.5/4.8 (assume follow the most advanced courses which schools are provided). If it is 4.6/4.8 up, it has great chance to go into T5.
I observed 2 years results, it seems true.
I was told the top colleges keep tracking some high schools GPA trend and courses, even what teachers told which courses. They collect those data and build their GPA models.