If I understand you idea, you want to :
dispay 10.0 if MyVar=100
display 10.2 if Myvar=102
and so on ...
To do that you can, in the settings of a rectangle (by example) write :
Category Text -> Content: %2.1f //display format for a REAL, with 2 digits before point and 1 digit after
Category variable -> Textdisplay : INT_TO_REAL(MyVar)/10 //conversion of the INT into REAL, then division by 10
Another solution could be :
Category Text -> Contente: %2.1f //display format for a REAL, with 2 digits before point and 1 digit after
Category variable -> Textdisplay : INT_TO_REAL(MyVar) //conversion of the INT into REAL
Conversion factor : 0.1 //Division by 10
It works ... but you can't change the value of MyVar directly by this rectangle. You can't have a text imput with a such equation.
If you want to change the value of MyVar, you have to add another rectangle close the display (I put it in the background under the first, letting it go a little beyond, so I can click on it).
In this second rectangle you can display MyVar with %d and configure a text input.
It's just an idea. Maybe there is a smarter solution ?