bearisgray

If I was doing this with 5-inch charm squares - assuming that they were cut "perfectly" - this is what I would do:

Cut as indicated in the drawings.

Theoretically, the unit should be 4-5/8 inches after the three pieces are sewn together. (Finished size - theoretically, should be 4-1/8 inches.

When sewing the two smaller pieces together, there will be "dog ears" when they are put together.

After sewing the three pieces together, I would trim the unit to 4-1/2 inches.

I don't have major problems sewing bias edges together - and I think the unit presses up very nicely when cut this way.

There will be some left-over pieces that can be used for other projects doing it this way.