Yes, you can. No, you shouldn't, both because it is unethical and because it is not in your favour.
There's obviously nothing to stop you doing this. However, from an ethical point of view it's dubious because you are misrepresenting your role in the paper in an attempt to make yourself look better. This, quite apart from anything else, should stop you doing it. Perhaps you've heard that you should present the best possible view of yourself in your CV, and I guess this is true, but it's missing a word it should be best possible honest view of yourself. It's fine to paint a rosy picture; it's not fine to be dishonest.
But perhaps you don't care about ethics. Consider this: it is more likely than not that those hiring you will look up some of your papers, they may even ask you about your contribution to them during the interview. What kind of impression do you think this will make? There are essentially too possibilities here:
- You're the kind of sloppy individual who didn't care to correctly represent themselves on their CV.
- You're the kind of reprehensible individual who would play down others contributions in order to make themselves look better.
Would knowing either of these things about someone you're considering hiring make you more likely to hire them? I think that's very unlikely. So really there are only two circumstances under which it could help you to do this:
- If those hiring you are to busy (or too lazy) to check your publications before hiring you.
- You have so many publications that they're not going to check down to this one.
The former case, I would say, is unlikely - publications matter and for any worthwhile job, they'll take at least the passing look it takes to realise you've misrepresented yourself - and, in the second case, why are you being so petty to misrepresent this publication anyway? It really doesn't matter.
Finally, in my opinion the difference between first author, and joint first author, is unlikely to be the deciding factor between being hired and rejected anyway so any gain you imagine you could make is very slight.