depends on the flow of traffic, and how busy it is. if its completely empty, i might do 10 over, if there are some other cars, ill keep up to their pace/go a little faster to pass, nothing ridiculous though.
I usually go 5 to 10 over but if some guy going really fast passes by me, i'll wait till hes like a quarter mile ahead and then speed up to his pace (unless hes going ridiculously fast). This gives the cop enough room to pull out and pull him over and by the time he pulls out i'll see him and slow down.
This strategy has actually paid off over the years, i've had two people pulled over that i was following in this way.
Don't think that just cause youre following someone means your free though. Don't get to close! I've seen cops pull over two cars many times in the past.