I don't have Numbers installed locally, so I'm doing this with Numbers on iCloud, but it should work the same.
There are the functions ROUND, ROUNDUP and ROUNDDOWN.
So if you have the following values:
A1: 1.36
B1: 1.21
In C1, if you do =SUM(A1,B1), you'll get the result 2.57
With the three round functions in D1, E1 and F1, you'll get:
Code:
ROUND(SUM(A1,B1), 0) = 3
ROUNDUP(SUM(A1,B1), 0) = 3
ROUNDDOWN(SUM(A1,B1), 0) = 2
The 0 indicates no decimal places, if you put a 1 in there, you get:
Code:
ROUND(SUM(A1,B1), 1) = 2.6
ROUNDUP(SUM(A1,B1), 1) = 2.6
ROUNDDOWN(SUM(A1,B1), 1) = 2.5
Play around with this until you get what you want. You can also try round before summing or the other way depending on what you want.