Is there a particular reason that you are using a float, for scientific calculations perhaps?

If you want to store financial/monetary values I would recommend that you use decimal.

Also, how did you declare your float?

If you are working to 2 decimal places (common for monetary values), if you insist on using floats then declare it like this:

float(15,2)

where 15 is the total length of the value including decimal places and 2 is the number of digits after the decimal point. Again I would recommend:

decimal(15,2).

To display the data after any calculations, I would use number_format():

$someValue = 426.98 * 3.333333;

echo $someValue; // 1423.26652434

$myCalculatedValue = number_format($someValue, 2, '.', '');

echo $myCalculatedValue; // 1423.27

http://php.net/manual/en/function.number-format.php

Hope this is some help.

EDIT:

I might add that if you are calculating exchange rates or share prices for example, you will need more than 2 decimal places, otherwise your calculations will be way out particularly as the amount increases.