How to round an embedded variable?

Hi!
I've made the following embedded data variable: ${gr://SC_6M4lPMHbDTjS885/WeightedMean}
I'm trying to figure out how I can get this variable to round to 2, and I've seen some other pages about the same topic, but still seem to be doing something wrong...thoughts?
I tried this and it's not working : ${ round ( gr://SC_6M4lPMHbDTjS885/WeightedMean , 2) }