try this. Place this code in .jsp file where the user enters order and press submit.
<%
//Invalidate cache code
response.addDateHeader("Expires", 1);
response.setHeader("Pragma","no-cache");
if (request.getProtocol().equals("HTTP/1.1")){
response.setHeader("Cache-Control", "no-cache, no-store, must-revalidate");
} else {
response.setHeader("Cache-Control", "no-cache");
}
%>