Yum Brand's  August Sales Up  NEW YORK (Reuters) - Yum Brands Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=YUM.N target=/stocks/quickinfo/fullquote"&gt;YUM.N&lt;/A&gt; on Thursday  said sales at U.S. restaurants open at least a year, or  same-store sales, rose 5 percent in the four weeks ended Sept.  4, led by strength at its Taco Bell and Pizza Hut chains and a  rebound at KFC.