How do you keep a mashup in tune using Tracktion?

Hi, please don't answer this if you're just looking to boost your points/don't know what you're talking about. So anyway i've been making mashups for about a year using Tracktion 3 and at this point i am getting pretty damn good at it, but i am having a real problem keeping my mashups in tune. What i am trying to figure out is if there is a built in feature in tracktion or a vst plugin that can help me keep two songs in tune with one another in a mashup, because as i said thats really the only thing keeping me from getting people into my tunes. P.s. i'm tonedeaf, so raising the pitch using tracktion's pitch shifter is out of the question unless there is some program that can use to tell me how much to shift it