hmmm, I guess you boss just isn't very progressive.
I'd learn css3/html5 as best as you can, as quick as you can. If your boss wont let you use it on his clients then you'll just need to make a whole stack of test sites/ external clients who are willing to try new things and experiment. current w3 estimates that 2nd quarter 2014, for HTML5 to reach "Candidate Recommendation." so...I for one am not going to sit on my arse til then because its not 100% supported. CSS2 still isn't 100% supported. If you dont know it by then (and thats roughly 3 years to go) you will be left behind as all the progressive developers will have been using it for years, and you'll end up doing webpages for the crappy corner store, rather than the big fry you really will want to tackle...tell your boss that.
at the very least CSS3 has been brought out in stages so that certain modules can be completed whilst css3 as a whole is still being developed.
there are quite a few of these modules which are supported across all browsers (with the exeption of the usual suspects - but like I said, CSS2 isn't fully supported by said browsers either...)