My transformation matrix gives me, for example, x = 0.06, y = 0.27 and z = -0.04 It does not make a lot of sense to me if this is in cm.
As @SteveO says, it could be any of them.
The units are linear mappable, then you could simply multiply for a scalar and change the units and the descriptions will be the same, even you could use percentage as a unit.
So in virtual frames (on simulations) the units has not to be definited, you could interprete the "neutral" units as you wish... say that the robot was 50% smaller than the real one, then if you simply multiply any position or the axis by 2 you will get the real scalar representation.
If you have x = 0.06, y = 0.27 and z = -0.04, and you say that 0.06 means meters, then all that you will get in future calculations will be in meters, but if you change your initial consideration and say 0.06 is inch then all the remainming calculations will be in inchs too.