It would be easier to add up the values first and then round it.
total = float(WebStorage.....) + float(WebStorage....) + ....
set text to round(total * 10) / 10
Actually I think if you add up the values into a variable and then set the text to the variable, it gets rounded automatically.
You could even use a loop to add up the values:
[attachment=0:2ay32aq3][/attachment:2ay32aq3]