Speaking as an Employment Counsellor, it might not only be the dreadlocks. When you go into apply, you are probably always self-coniously thinking "Oh, these assholes aren't going to hire me because I have dreadlocks" By you even thinking, you are going to make them think it with your energy. Also, most people's knowledge of dreadlocks comes with stereotypes, like anything else. They also are not the most hygenic.
If you were attemping to work at any food establishments (frontline or kitchen), your dreads would put customers off and it would reflect poorly on the business, whether you were the most incredible employee or not.
You have to find out where you fit. Honestly, cutting your dreads off would get you much further in your search, but that's depends on what kind of job you want. If you are not willing to cut them, brain storm about places where you would like to work where it may be acceptable (Eg, music stores, certain retail outlets and shops, call centers etc) It's your choice, do what makes you happy and Good Luck.