<?php
$data_original = '2015-05-01';
$dataVencimento = new DateTime($data_original);
$dataVencimento->add(new DateInterval('P5D'));
echo 'Data original: '. $data_original .PHP_EOL;
echo 'DateTime & DateInterval: '. $dataVencimento->format('Y-m-d') .PHP_EOL;
echo 'Date & strtotime: '. date('Y-m-d', strtotime($data_original .'+ 5days'));
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