The "Plus/Minus" grading system is used at UBC (Vancouver, Canada), as well as at many other post-secondary institutions in Canada. Here is the percentage/mark/GPA value breakdown used here:
Percentage (%) // Letter Grade // GPA value
90-100  //   A+  //  4.33
85-89    //   A    //  4.0
80-84    //   A-   //  3.67
76-79    //   B+  //  3.33
72-75    //   B    //  3.00
68-71    //   B-   //  2.67
64-67    //   C+  //  2.33
60-63    //   C    //  2.0
55-59    //   C-   // 1.67
50-54    //   D    // 1.00 ?? (not sure)
0-49      //   F (fail)  //  0.00
During elementary & secondary school, this grading system was not used, at least not in my schools -- around here, grading practices can vary from school to school within the same district.
- Jen

AGD alumna