How to round my calculation field to 2 decimal places?

Example: Calculate the average weight of 'weight 1' and 'weight 2' 

Step 1 - In the calculation field, build the formula, e.g. 

(data["weight 1"]+data["weight 2"])/2

Step 2 - Specify how many decimal places you want to round to using the below where 2 at the end is the number of decimal places. 

fixed([insert formula] ,2)

It should look like this:

fixed((data["weight 1"]+data["weight 2"])/2,2)