You can do that by further increasing the height of the cell - you'll need to play around with it until it looks centered. Unfortunately, CR does not have an option to vertically center fields to a text object and this is the only workaround.
You can use the same display string logic to center align the summary fields as well. The only issue is that your numbers would need to be converted to text:
" " & Totext(CurrentFieldValue)
-Abhilash