Given your location, pay close attention to the restrictions on magazine size when open carrying, unless you have a Concealed Handgun Permit.
You have no duty to volunteer information regarding the fact that you are openly carrying or carrying concealed, and most of us will never mention anything about being armed if we are stopped. If asked, however, you must not lie. It depends on the phrasing of the question, however. If the LEO asks if you are armed/carrying/have a weapon, etc, you must answer truthfully. If the LEO asks if you have anything illegal in the car or some other non-specific question, you could respond with "No, there is nothing illegal in my vehicle," assuming that is a truthful answer.