Rounding
The round( ) function uses 4/5 rounding rules to round up or down a value to a given precision:
float round(float value [, integer precision])
Rounding by default is to zero decimal places, but the precision can be specified with the optional precision argument. The 4/5 rounding rules determine if a number is rounded up or down based on the digits that are lost due to the rounding precision. For example, 10.4 rounds down to 10, and 10.5 rounds up to 11. The following examples show rounding at various precisions:
echo round(10.4); // prints 10 echo round(10.5); // prints 11 echo round(2.40964, 3); // prints 2.410 echo round(567234.56, -3); // prints 567000 echo round(567234.56, -4); // prints 570000