hey @PonderingSoc well to be honest there isnt one gpa or gre score that would make you a shoe-in for grad programs, your resume, overall research experience, letters of reference and letter of intent all play a summative role in your admissions process. BUT with that said generally, for canada most graduate programs are asking for minimum 3.7 in final two years but to be safe aim for 3.8 that should make you very competitive for most grad programs. Also for gre aim for a balanced score somewhere in the range of 310-320 and above. so something like 155, 160 or 156 159...someting that is balanced, the gre isnt super important but it is a sort of filter you need to get through. Also make sure, make SURE! you have some solid research experience, relevant research experience as well, something that you can write about and say why this particular experience makes you a strong candidate for the particular program. Its all about building your resume, and profile so dont fret if this seems overwhelming, take it one step at a time and try to build your profile one step at a time, next thing you know you're in grad school.
Best of Luck!