I'm not basing it on fights or weigh ins, there was a set of promo pictures from the Strikeforce days where they were nose to nose and Tate clearly looked taller (not much taller, but taller) from multiple angles. Miesha herself claims to be 5'6, she may be 5'6 1/2 but Ronda is 99% in my mind not 5'7.
Again, why the strong faith in UFC measurements over Strikeforce's etc? They have made terrible mistakes before (Amanda Nunes listed as 5'5, Carwin as mentioned), and I really really wouldn't put it past them to exaggerate certain fighters' height by an inch. Faber is clearly shorter than Frankie and listed as 5'6.