I tried this: http://jsfiddle.net/ilyaD/KGcC3/
HTML:
Alternative "fake" solution if you have a list with options similar in text length (page select for example):
padding-left: calc(50% - 1em);
This works in Chrome, Firefox and Edge. The trick is here to push the text from the left to the center, then substract the half of length in px, em or whatever of the option text.
Best solution IMO (in 2017) is still replacing the select via JS and build your own fake select-box with divs or whatever and bind click events on it for cross-browser support.