No, because parents raising their kids to be honest and then turning around and lying them would be setting a bad example. But, if it is something that deals with us, then I think that we need to know the truth. Yes, because they don't need to know the truth sometimes. It might hurt them. There is no reason for parents to teach children about honesty when they are lying.
Younger kids look up to their parents.
Parents should be good examples, not bad examples. No, it is never OK for your parents to lie to you. You would want them to tell you the truth, just like they would want you to tell the truth. It is OK if they are trying to protect the child. But, it is not OK if they are trying to cover up something, especially a serious issue.