I've never been satisfied with the old well-known method to create pentagons from square papers, for several reasons:
1. Most of papers I use are taken from A-format papers;
2. The method is quite inaccurate: in fact, it's based on arctg(3), that gives an angle of 71,57°;
3. Every time, it is necessary to adjust the proportions and the angles manually, and this is frustrating.
My method is much more accurate, because I've been able to get an angle of 71,98°, which is quite close to the 72° necessary to get a perfect pentagon, and because I've been able to use the extra paper given by A-format papers.
So, have a good folding and, for once, a good cutting!