It might be worth mentioning that you can simplify the process a bit by inputting your dimensions as a formula.
Take your example:
I would do the following:
Ensure that the aspect ratio is locked (padlock icon is locked in dimension bar)
Control-a (select all)
Click at the end of the W or H (doesn’t matter which one since you locked aspect ratio) and add “*.136/.125”
Hit enter. All done!
it’s a very small “improvement”, but once you start thinking like this, you can take advantage of the fact that Inkscape accepts formulae almost everywhere. Want to make a pentagonal arrangement of objects, but forget how much to rotate each copy? Object->transform, select rotate, and for degrees put in “360/5”, voila.
OK, so maybe that was easy, 72 degrees is nice and even… but slightly more complicated: same situation but you’re making a 13-sided figure? Wait, what, you don’t have that memorized? No worries, “360/13”, boom. (it’s 27.692 degrees, of course. 
)
Want to move something to the left by 1/15th of an inch? Ensure your doc is in inches, select the object, click X position box, add “-(1/15)” to whatever is in there, hit enter.
It’s useful for all kinds of things, go forth and multiply!
(wait that came out wrong. oh well 
)