How to round a number to a chosen integer

In Denmark we have an odd grading system that goes as follows. [-3,00,02,4,7,10,12] Our assignment is to take a vector with different decimal numbers, and round it to the nearest valid grade. Here is our code so far.

import numpy as np

def roundGrade(grades):    
    if (-5<grades<-1.5):
        gradesRounded = -3
    elif (-1.5<=grades<1.5):
        gradesRounded = 00
    elif (1.5<=grades<3):
        gradesRounded = 2
    elif (3<=grades<5.5):
        gradesRounded = 4
    elif (5.5<=grades<8.5):
        gradesRounded = 7
    elif (8.5<=grades<11):
        gradesRounded = 10
    elif (11<=grades<15):
        gradesRounded = 12
    return gradesRounded

print(roundGrade(np.array[-2.1,6.3,8.9,9]))

Our console doesn't seem to like this and retuns: TypeError: builtin_function_or_method' object is not subscriptable

All help is appreciated, and if you have a smarter method you are welcome to put us in our place.