Depends on your poly. For my poly, here's how it works.
A = 4
B+ = 3.5
B = 3
.
.
.
so on
So your GPA for this 5 modules is
(4 + 4 + 3 + 3.5 + 2)/5 = 3.3
And say you have more done 4 more modules in the next semester, say
9 with grades like A, B+, B+, B
GPA = (4 + 4 + 3 + 3.5 + 2 + 4 + 3.5 + 3.5 + 3)/9 = 3.89
It's cumulative... (at least for RP)