Rounding numbers with respect to percentages

I am trying to dynamically calculate percentages and return the results rounded off to the first decimal place. I tried using the "round($num,1) " -- but the results don't always add up to 100% "intval($num)" -- doesn't account for percentages that are less than 1 "floatval($num) -- doesn't allow me to round off to a specificed decimal place, which in return gets me back to the same problem as "round" How can I round off to the first decimal place making sure they add up to 100%? Thanks, Ron