Hi Isabelle,
You can use the table panel equations feature to do this. First, create a new column (I made mine string, but it can also be double). Then, click into a cell in the column and click on the equation editor "f(x)". That will bring up a dialog you can use to create an equation. I used the ROUND function, entered the column I wanted to round, then selected the number of digits. Then, apply that to the entire column. Now you can change your label mapping to your new column.
Hope this helps!
-- scooter