<?php

function getValueBills($num)
{
    $arr = [
    5000=>0,
    1000=>0,
    500=>0,
    100=>0];
    $x=0;
    while(true){
        if($num <= 0 || $x>10000){
            break;
        }
        $x++;
        foreach($arr as $ri => $rv){
          $s = $num / $ri;
           if(is_int($s)){
               $num -= $ri;
               $arr[$ri] += 1;
               break;
            }
        }
    }    
    return $arr;
}

function getBillsValue($bills){
    $rvalue = 0;
    foreach($bills as $item => $value){
        $rvalue += $item * $value;
    }
    return $rvalue;
}

$value = 17700;
var_dump($value);
$bills = getValueBills($value);
$value = getBillsValue($bills);
var_dump($bills, $value);