Geometric properties can be used labeling where they can be rounded using the XFM Evaluator Expression XFM.Round. 

For example, the following will round Geometry_Area to two decimal places: 

[XFM.Round([Geometry_Area],2)]  

This expression can also be used to convert Geometry_Area to another unit of measure such as acres.

The following will convert Geometry_Area from square feet to acres and round the resulting value to 4 decimals.

[XFM.Round(([Geometry_Area] * 0.0.00002296),4)]

or

[System.Math.Round([Geometry_Area] * 0.00002296,4)]

For converting square meters to acres, use this value:  0.00024711.

Note, while this article only shows labeling the Geometry_Area, the same principles can be used for any numeric property.