Illustrator :: Cannot Manually Set X Y Coordinates

Sometimes I can manually set the x & y coordinates, and sometimes I can't: I change the number from say 54.0001 to 54, and Illustrator changes it back to 54.0001. Or, more commonly, it will not allow me to specify a float when the coordinate is an integer ( 54 -> 54.1 ).
 
The layours/shapes are not locked and I disabled all snapping options (snap to grid, snap to point, snap to guide).Why does it decide to work sometimes and not others?
 
Also, why, even when I have all the snaps enabled, does Illustrator insist on setting coordinates to a float that is JUST off of what it should snap to? Say I have a Guide and the left side of Shape A at x-coord 60; Illustrator absolutely refuses to align the right side of Shape B to x-coord 60 when dragging. Instead it decides 59.9897 is better. Both shapes are simple, are solid/filled, and have no stroke or effect/filter.
 
Even if I select Shape A and Shape B (Shape B is a copy of Shape A) and use the align palette (specifying Shape A is the key object), it will still set the x-coord of Shape B to 59.9897 instead of 60. WHY?
 
I noticed Illustrator setting erroneous/illogical xy coords since CS3 (it might have existed earlier), but I've always been able to force the x-coord manually to be the position I want; until now.