Regardless of whether you pass the test, or whether becoming a CHP can get you a promotion or a higher paying job, the course is deductible as long as the training is related to your work and will make you more proficient in your work.
It is NOT deductible if the course will qualify you for a different line of work OR if it is required as a condition of your current job.
I know that last part doesn't make a lot of sense, so I'll try to explain the rationale behind it.
If you go to college to become a dentist, and then get a job as a dentist - even though you were not a dentist before taking the schooling - dental college is not deductible. If your buddy the dentist hires you to be a dentist - but you haven't gone to dental college - and he requires that you complete dental college in order to keep your job as a dentist and start treating patients, then dental college is not deductible. If you are a dental hygienist, and you go to dental college, SOME of the courses would be deductible to the extent that they make you a better hygienest, but those which go beyond that level would not be. The line between those would be a little blurry. This part of the regulations is intended to prevent people for taking jobs they are not qualified for (in name and title but not in practice) just so they can deduct the required education for that job as work related. Otherwise every college student would be able to deduct all tuition for every course they take as long as they eventually get a job after they graduate. So, basically any education that would be considered as the essential education to qualify for a job - even if you already have that job - is not deductible. Any education that increases your proficiency in a field that you already work in is deductible.
So, in your case, if you just got a job as an RPM, and they require you to pass the CHP exam in order to keep the job, then the training is not deductible. But, if you took the course in order to improve your knowledge in the job you have and to become more proficient at it, (which would of course lead to possioble promotions or better jobs) then you can deduct the cost of the course.