As MadProgrammer said, This can be easily done with XPath if you are passing a Node. So, in my case I passed the Parent Node / Document that I took to derive the NodeList as follows.
Node node = (Node) XPathFactory.newInstance().newXPath().compile(stringXPathExpression).evaluate(nodeOrDocument, XPathConstants.NODE);
To get a String :
String currencyCodeInTotal = XPathFactory.newInstance().newXPath().compile(stringXPathExpression).evaluate(node);
Reference : http://viralpatel.net/blogs/java-xml-xpath-tutorial-parse-xml/