Depends on the state.
AFAIK, you never have to comply with roadside/field sobriety tests. And you should not. They've already decided to arrest you by the time they ask and are just letting you incriminate yourself when you start the test. However, as far as doing the breath or blood test, in some states, you can still get a restricted license after a DUI conviction IF you did not refuse the blood/breath test. If you refuse, that's an automatic one year suspension with no restricted privileges.
So, depending on the state, even if you know you're over the limit, if it's not egregious and you haven't caused an accident or hurt anyone, doing the breath/blood test can help make your suspension a little more palatable, so you can get to work and earn the $15-20k the whole ordeal will end up costing you. I had a buddy refuse the breath test and he ended up having to move to within walking distance of his workplace because of it - one year suspension with no restricted privileges. I also refused, but it was in a different state and part of my plea deal got them to keep it in-state and not report to my DMV or insurer.