Why are my Dimensions "Approximate" AND Exact?

I’m working with a fairly simple model that “seems” to have exact dimensions. When I measure with the tape measure tool it’s showing exact dimensions on both of my axis sides. But when I try to create a rectangle around the same dimensions, the measurements area is showing ~approximate measurements.

This usually tells me something is off in the model. Why would SU tell me it’s approximate and exact at the same time?

Attach the model.

You should increase your dimension precision and turn off Length Snapping in the Window>Model Info>Units dialog.