We’ve tried many different methods to set precision for a number variable (specifically a currency amount) and we’d like to share the best method we’ve found:

number_format(
   {number},
   {precision},
   'decimal_separator',
   '1000s_separator' );

Example:

number_format( $number, 2, '.', ',' );

Hope this helps!

We have also tried using round( $number, {precision} ) but it ignores zeros(0) within the precision numbers.

Example:

$number = 9.90;
round( $number, 2 ); // returns: 9.9