I worked as a financial auditor for a state government for a few years and one of the things I did was audit cities and counties. When you audit a city, you typically audit the police department as well. One of the things I needed to check was whether or not the tickets that the police department wrote were real and that the money went where it was supposed to go.
There are two kinds of tickets, traffic and criminal and one day I spent the day looking through traffic tickets to find out how fast you really needed to be going to get pulled over by the cops. Of course, during an audit you typically never go through ALL of anything, you just test a reasonably sized sample. Tickets were no different, but I went above and beyond in this research. In the several cities that I audited, you needed to be going 10 miles over the speed limit to get ticketed (for the most part). Most of the tickets were actually for going over 15, but 10 was common as well. Getting a ticket for going 5 mph over the speed limit was actually incredibly rare. It did happen, but incredibly rare.
Just keep that in mind as you are driving. If you are going 10 miles over the speed limit, you are at a pretty high risk of a cop pulling you over. If you are going 5, you are pretty low risk. If you need to speed, keep it around 5!
