Do I have to do them? No.
What do the tests consist of?
1. The HGN Eye test (they are looking for nystagmus or an involuntary jerking of the eye which could indicate the presence of alcohol in the blood.)
2. The Walk & Turn Test. Walk in a straight line 9 steps; turn around and walk back 9 steps.
3. The One Leg Stand. Stand on the leg of your choosing and point your toe straight ahead and keep your foot 6 inches off the ground and leave it there while counting. It is a 30 second test although the officer won't tell you when to stop or that it is a 30 second test. Most people put their foot down prior to the 30 seconds which seems like a long time and then you have halfway failed.
Field Sobriety Tests, breath tests that may or may not be accurate as to a blood alcohol content at the time of driving (not an hour later when the breath test is given), bad or good driving, being rude or polite during the investigation, being impatient, bloodshot eyes, slurring speech or speaking articulately.....ALL of these are equal factors that lead to non-impairment or impairment.
It is not illegal to drink and drive. It is illegal to drive impaired. And that is the issue. If you do not take the field tests they will arrest you based on what they perceived as bad driving. If you think you can prove them wrong by doing well on the field tests that you have never attempted to do before then by all means give it a shot. Or you can take the tests and likely look impaired.
The short of the long is that you do not have to take any tests offered to you if you do not want.