And, unless you are sitting some theory exam where they try to trip you up with cross wind or tailwind component, in a country where the variation is only in the order of 5 to 10 degrees, it is hardly worth considereing. I never yet found a wind direction absolutely constant, except totally calm. Just take off and land into what looks like the best headwind component if you possibly can and if you can't, make sure the runway is long, wide and hopefully straight, with any slope in your favor.
Runway direction numbers are rounded off to the nearest 10 degrees magnetic and they go outside that limit as the variation changes over the years. But the painters don't rush out and paint new numbers on the threshholds as soon as the difference hits 11 degrees, so it's all a bit academic to be splitting wind direction down to the nearest few degrees. Exam theory, but you need to know it to pass the IREX etc. You may even get the occasional line check capt who can remember it and so asks it, if it amuses him to delve at that level.
Now, if you ever get up to Canada, where the variation can be huge and change over a short distance, everything is in degrees tru, including the runway direction itself.