The print centering is intended to simulate a poster or sign (as I am sure you are aware). It's a visual thing and should not be replicated in braille. In this case, what is important is what the sign is saying. You have two options (as I see it). You can box it (to set it off from the text more) and then do the first line as a heading and the rest as either a list or a paragraph...Or you can treat it as displayed, again with a heading and a list or paragraph (with adjusted margins).