change values within a xml node

changeValueXmlNode

               //parse the XML, might as well use Xpath to avoid dupe root nodes.... ughhhhh
                System.Xml.XPath.XPathDocument xmlResults = new System.Xml.XPath.XPathDocument(customObjectThatHasXmlData.Data.InnerXml.ToString());
                System.Xml.XPath.XPathNavigator xmlResultsNav = xmlResults.CreateNavigator();

                System.Xml.XPath.XPathExpression xmlResultsExpression;
                xmlResultsExpression = xmlResultsNav.Compile(@"/Data/result xmlns=""/time_stamp"); //in this case was trying to get the Tstamp
                System.Xml.XPath.XPathNodeIterator xmlResultsNavIterator = xmlResultsNav.Select(xmlResultsExpression);

                while(xmlResultsNavIterator.MoveNext())
                {
                    if (xmlResultsNavIterator.Current.Name.Equals("time_stamp"))
                    {
                        DateTime newDT = RoundUp(DateTime.Parse(xmlResultsNavIterator.Current.Value), TimeSpan.FromMinutes(5));
                        xmlResultsNavIterator.Current.SetValue(newDT.ToString());

                    }
                }
                
                //source: http://www.codeproject.com/Articles/9494/Manipulate-XML-data-with-XPath-and-XmlDocument-C

foreach (System.Xml.XmlNode node in mbsSearchResultData.Data)
{

                foreach (System.Xml.XmlNode singleChildNode in node.ChildNodes)
                {
                    if(singleChildNode.Name.Equals("time_stamp"))
                    {
                        DateTime newDT = RoundUp(DateTime.Parse(singleChildNode.InnerText), TimeSpan.FromMinutes(5));
                        //newDT = newDT.ToUniversalTime();       //.ToLocalTime();
                        singleChildNode.InnerText = newDT.ToString();
                        singleChildNode.InnerXml = newDT.ToString();
                    }

                }         

            }