if you float you use your spells to half- container flow so you lose the inheritance with the parent so the auto margin does not detect the width of its parent
exemple of template to center ul :
<!DOCTYPE html>
<html>
<head>
    <title>test ul center</title>
    <style type="text/css">
    #wrapper{
        margin: 0 auto;
        max-width: 1200px;
    }
    #navigation{
        margin: 0 auto;
        width: 40%;
    }
    #navigation ul{
        vertical-align: top;
        display: inline-block;
    }
    </style>
</head>
<body>
<div id ="wrapper">
    <nav id="navigation">
      <ul>
        <li class="titleLi">About Us</li>
        <li><a href="" target="">Team</a>
        </li>
        <li><a href="" target="">Blog</a>
        </li>
        <li><a href="" target="">Contact</a>
        </li>
        <li><a href="" target="">Support</a>
        </li>
      </ul>
      <ul>
        <li class="titleLi">Download</li>
        <li><a href="" target="">for iOS</a>
        </li>
        <li><a href="" target="">for Android</a>
        </li>
      </ul>
      <ul>
        <li class="titleLi">Legal</li>
        <li><a href="" target="">Terms and conditions</a>
        </li>
        <li><a href="" target="">Privacy police</a>
        </li>
      </ul>
    </nav>
</div>
</body>
</html>