note 38928 modified in function.round by danbrown

To round any number to a given number of significant digits, use log10 to find out its magnitude: <?php round($n, ceil(0 - log10($n)) + $sigdigits); ?> Or when you have to display a per-unit price which may work out to be less than a few cents/pence/yen you can use: <?php // $exp = currency decimal places - 0 for Yen/Won, 2 for most others $dp = ceil(0 - log10($n)) + $sigdigits; $display = number_format($amount, ($exp>$dp)?$exp:$dp); ?> This always displays at least the number of decimal places required by the currency, but more if displaying the unit price with precision requires it - eg: 'English proofreading from $0.0068 per word', 'English beer from $6.80 per pint'. --was-- To round any number to a given number of significant digits, use log10 to find out its magnitude: round($n, ceil(0 - log10($n)) + $sigdigits); Or when you have to display a per-unit price which may work out to be less than a few cents/pence/yen you can use: // $exp = currency decimal places - 0 for Yen/Won, 2 for most others $dp = ceil(0 - log10($n)) + $sigdigits; $display = number_format($amount, ($exp>$dp)?$exp:$dp); This always displays at least the number of decimal places required by the currency, but more if displaying the unit price with precision requires it - eg: 'English proofreading from $0.0068 per word', 'English beer from $6.80 per pint'. http://php.net/manual/en/function.round.php