No-follow links tell google NOT to flow weight from the website to the backlink.. So, they can't help you increase your page rank. But... They can really help you get a great SERP for your keywords in Google, because each backlink (no matter it is a do-follow or no-follow!) is a +1 to the total backlinks to your website using the keyword you are trying to rank for
Nofollow links will also come under backlinks according to GWT but nofollow will not give any effect to your website's page rank. However, any seo professional will suggest you to have a natural linking strategy. To parallel the linking from both dofollow and nofollow links then only, it will be considered as natural reputation.