PHP round( ) Function

While dealing with problems which have values consisting of a very high number of decimal digits such as (121.76763527823) we often come up with a problem of rounding them up. Rounding them up manually can be a very time consuming and erroneous practice. In place of that, an inbuilt function of PHP i.e round() can be used. 
The round() function in PHP is used to round a floating-point number. It can be used to define a specific precision value which rounds number according to that precision value.Precision can be also negative or zero. 
The round() function in PHP has 3 parameters which are number, precision, and mode among which the latter two are optional parameters.The round() function returns the rounded value of the argument passed.

Syntax: 

float round($number, $precision, $mode);

Parameters: It accepts three parameters out of which one is compulsory and two are optional. All of these parameters are described below:  

1. $number: It is the number which you want to round.
2. $precision: It is an optional parameter. It specifies the number of decimal digits to round to. The default value of this parameter is zero.
3. $mode: It is an optional parameter. It specifies a constant to specify the rounding mode. The constant can be one of the following: 
   
   • PHP_ROUND_HALF_UP: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision away from zero.
   • PHP_ROUND_HALF_DOWN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards zero.
   • PHP_ROUND_HALF_EVEN: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest even value.
   • PHP_ROUND_HALF_ODD: This mode tells to round up the number specified by parameter $number by precision specified by parameter $precision towards nearest odd value.

Return Value: It returns the rounded value.

Examples:  

Input : round(0.70)
Output : 1

Input : round(0.708782)
Output : 0.71

Input : round(-3.40)
Output : -3

Input : round(-3.60)
Output : -4

Below programs illustrate the working of round() in PHP:

• When a parameter is passed with default precision i.e. '0':

<?php

echo(round(0.70));

?>

Output:

1

• When a parameter is passed with a specific precision value:

<?php

echo(round(0.70878, 2));

?>

Output:

0.71

• When a negative value is passed as a parameter:

<?php

echo(round(-3.40));

?>

Output:

-3

• Passing parameters with mode:

<?php

// round to nearest even value
echo(round(7.5,0,PHP_ROUND_HALF_EVEN));
echo "\n";

// round to nearest odd value
echo(round(7.5,0,PHP_ROUND_HALF_ODD));
echo "\n";

// round towards zero
echo(round(7.5,0,PHP_ROUND_HALF_DOWN));
echo "\n";

// round away from zero
echo(round(7.5,0,PHP_ROUND_HALF_UP));

?>

Output:

8
7
7
8

Important Points To Note: 

• round() function is used to round floating-point numbers.
• A specific precision value can be used to get the desired results.
• Precision value can also be negative or zero.

Reference: 
http://php.net/manual/en/function.round.php