Как вставить функцию "round" в php код ?

<?php

ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');

function http_get_contents($url, $post_params = false) {
	$data = false;

	if( stripos($url, "http://") !== 0 AND stripos($url, "https://") !== 0 ) {
		return false;
	}

	if( function_exists( 'curl_init' ) ) {	
		$ch = curl_init();
		curl_setopt( $ch, CURLOPT_URL, $url );

		if( is_array($post_params) ) {
			curl_setopt($ch, CURLOPT_POST, 1);
			curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($post_params));
		}

		curl_setopt( $ch, CURLOPT_RETURNTRANSFER, 1 );
		curl_setopt( $ch, CURLOPT_CONNECTTIMEOUT, 5 );
		curl_setopt( $ch, CURLOPT_SSL_VERIFYPEER, false);

		$data = curl_exec( $ch );
		curl_close( $ch );

		if( $data !== false ) return $data;
	} 

	if( preg_match('/1|yes|on|true/i', ini_get('allow_url_fopen')) ) {
		if( is_array($post_params) ) {
			$url .= '?' . http_build_query($post_params);
		}

		$data = @file_get_contents( $url );

		if( $data !== false ) return $data;
	}

	return false;	
}

$responce = http_get_contents("https://api.privatbank.ua/p24api/pubinfo?exchange&coursid=5");

if( $responce ) {
	$xml = new SimpleXMLElement($responce);
	
	echo '<pre>';
	echo $xml->row[2]->exchangerate['ccy'][0] . ': ';
	echo number_format((float)$xml->row[2]->exchangerate['buy'][0], 2) . ' - ';
	echo number_format((float)$xml->row[2]->exchangerate['sale'][0], 2) . '<br />';
	echo $xml->row[0]->exchangerate['ccy'][0] . ': ';
	echo number_format((float)$xml->row[0]->exchangerate['buy'][0], 2) . ' - ';
	echo number_format((float)$xml->row[0]->exchangerate['sale'][0], 2) . '<br />';
	echo $xml->row[1]->exchangerate['ccy'][0] . ': ';
	echo number_format((float)$xml->row[1]->exchangerate['buy'][0], 2) . ' - ';
	echo number_format((float)$xml->row[1]->exchangerate['sale'][0], 2);
	echo '</pre>';
}

?>