There was a time when I almost considered certification a guarantee that the candidate didn't have experience. A lot of application programmers seemed to be taking the exams and pretending that they had been working as dba's for years. Fortunately that doesn't seem to be the case now (but the interviews were fun) but it's still pretty meaningless in real terms - especially as there are sites that allow you to cheat.
>> What % increase in salary can one expect after being certified?
I wouldn't expect any - it may mean the difference between being considered for a job or not but highly paid jobs would depend on experience.
>> Do employers really care about certification?
Some appear too but I never have.
As/if we drop further into depression anything that widens your job prospects may be useful.
DTS - only when needed and never to control.