I'm in Western Canada at UBC, and we only go by percentages/letter grades. I have two courses left in my undergraduate degree, which wraps up in just a few weeks!
As of this semester, when my percentages/letter grades are converted to the 4.33 GPA scale, I'm an estimated 4.1; on the 4.0 GPA scale I'm estimated at somewhere in the 3.8-3.9 range. The reason I say estimated is 1) UBC doesn't calculate GPA, so I only have a rough rubric to estimate with, and 2) depending on the grad school you are applying to, some will analyze your transcript and calculate a GPA according to their own rubric rather than a "standard" one.
Others have already mentioned that your GPA is not the sole factor. Depending on what you want to go to grad school for, the following will also be important (in no particular order): specific extracurriculars, your GRE score (if needed for your program), research/volunteer experience in your faculty of interest, your academic/professional references, and the strength of your letter of intent. At some schools, if a prof really likes you/wants to work with you and supervise you, he or she might overlook a slightly lower GPA or GRE score and admit you anyway. No one's perfect, and they know that. However, with lots more people getting undergraduate degrees than ever before, it can be very competitive to get a supervisor for grad school. If you feel that you're disadvantaged with respect to your academic performance, now is the time to foster professional relationships at your university with faculty members. Get to know their areas of interest, take classes with the ones you'd ideally like to work with, do well in their classes and show active interest in what they are interested in. Whether your grades are strong or not, that will still take you a long way.
I hope that helps!