round number to nearest 0.2 with PHP

Question

I'm creating this rating system using 5-edged stars. And I want the heading to include the average rating. So I've created stars showing 1/5ths. Using "1.2" I'll get a full star and one point on the next star and so on...

But I haven't found a good way to round up to the closest .2... I figured I could multiply by 10, then round of, and then run a switch to round 1 up to 2, 3 up to 4 and so on. But that seems tedious and unnecessary...

Answer 1

round(3.78 * 5) / 5 = 3.8

Answer 2

A flexible solution

function roundToNearestFraction( $number, $fractionAsDecimal )
{
     $factor = 1 / $fractionAsDecimal;
     return round( $number * $factor ) / $factor;
}

// Round to nearest fifth
echo roundToNearestFraction( 3.78, 1/5 );

// Round to nearest third
echo roundToNearestFraction( 3.78, 1/3 );

Answer 3

function round2($original) {
    $times5 = $original * 5;
    return round($times5) / 5;
}