How to make one object fully cover another and how to get rid of fuzzy edges/corners in Inkscape?

Here is the thing: folder2.svg is created by me, and folder1.svg - by someone else. As you can see on the screenshot the first icon looks crisp and nice, and my icon has fuzzy edges and coners, the background object isn't fully covered, although the objects in my folder2.svg file have the same size:

Can someone, please, help me solve this problem? How do I make such fancy icons as folder1.svg?

Thanks.