PHP - Chances of winning with float percent values smaller 1

I'm building a system that depends on a correct percentage winning chance.
After trying it myself, and with many solutions from other asked questions.
I not found a single solution that seems to come close, to the chance the percantage indicates.
In my best test, I got between 30%-39% wins on 100k trys with a chance of 0.6%.
(currently the lowest chance is about 0.025%)
Wouldn't matter to me if the chance would be around 1-3%, but 30%-39%?

function randChance($percent){
    $number = 100;
    $percent *= $number;
    while(floor($percent) != $percent){
        $number *= 10;
        $percent *= 10;
    }
    $rates = [$number,$percent];
    for ($i = 0; $i <= count($rates); $i++) {
        $rate = $rates[$i] * 100;
        for ($j = 0; $j <= $rate; $j++) {
            $chance[] = $i;
        }
    }
    shuffle($chance);
    $rnd = mt_rand(0,(count($chance)+1));
    return $chance[$rnd];
}