UnitedHealthcare Settles Medicare Charges  WASHINGTON (Reuters) - UnitedHealth Group's &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=UNH.N target=/stocks/quickinfo/fullquote"&gt;UNH.N&lt;/A&gt;  UnitedHealthcare Insurance Co. has agreed to pay \$3.5 million  to settle charges that it defrauded the Medicare program, the  Justice Department said on Monday.