Gold pressed latinum

gpl.php

<?php
$usd = 29.99;

$slip = 2; // 1 slip = 2 dollars
$strip = $slip * 100; // 1 strip = 200 dollars
$bar = $strip * 20; // 1 bar = 4000 dollars

$result = array();

$bars = floor($usd / $bar);
if ($bars >= 1) {
	$result[] = $bars . ' bars';
	$usd = $usd - $bars * $bar;
}

$strips = floor($usd / $strip);
if ($strips >= 1) {
	$result[] = $strips . ' strips';
	$usd = $usd - $strips * $strip;
}

$slips = ceil($usd / $slip); // round up here
if ($slips >= 1) {
	$result[] = $slips . ' slips';
}

var_dump($result);