The imprecision is due to floating point arithmetic. 0.01, 0.05 and 0.03 are all floating point literals. Not every number (in fact, very few numbers) can be represented precisely in floating point.
For example, 0.5 can be but, 0.06 cannot. As a rule of thumb the first 15 significant figures will be correct.
For more details, see http://en.wikipedia.org/wiki/Floating_point