What is the significance of Jordans lies?

In some ways similar to the inconsistency and tendency to use other people, Jordan's dishonesty only serves to heighten the impression of her worldview based entirely on what she feels is good for her or what she wants at the moment. She is meant to be seen as amoral and selfish and her lying to Nick and to others helps to strengthen that impression.

In some ways it also connects to the fact that basically everything about her is false, both her words as well as her actions and the act she puts on for the world.