It's not uncommon for children of all ages to tell lies at some point in their life. Children ages three, four and even five years old will see make believe stories and want to tell tall tales, sometimes it's simply just entertaining and fun for them. As children start to grow older, adolescent age, they start to tell lies that are, more than likely, self-serving, often to get out of trouble. Children do, also, start to have a bit of confusion between a lie that gets them out of trouble versus a lie that is to protect someone's feelings.
One of the things we have to remember as parents that if children are lying very frequently and very consistently, that there may be a bigger problem that needs to be considered. Children that are lying, in addition to having other behavioral difficulties, really should be brought with their parents to meet with a clinical professional. Remember that, at some point, parents have to sit down with their children, and they have to help children understand the importance of telling the truth. And there do need to be some consequences involved in helping to steer children in the right direction of the truth.