<script>

function confirmTransfer() {
  var tasks = "{!totalTasks}";
  var matches = "{!totalMatches}";
  var contacts = "{!totalContacts}";

  var transfer = confirm("Are you sure you wish to transfer: " +
    tasks + " tasks, " + matches + " matches, and " + contacts " contacts?");

  if (transfer) return true;
  return false;
}

function confirmCancel() {
  var isCancel = confirm("Are you sure you wish to cancel?");
  if (isCancel) return true;

 return false;
}
</script>

<apex:commandButton action="{!cancel}" value="Cancel"
onclick="return confirmCancel()"immediate="true"/>
<apex:commandButton action="{!step4}"  value="Transfer"
onclick="return confirmTransfer()" immediate="true"/>