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>