You can edit the HTML by hand to say <td align="right"> in the cell, or hilight the text and use whatever justification tool your program uses for text.
The problem only exists in Safari because of a bug in Safari (or more precisely, a bug in the WebKit rendering engine that Safari uses; Google Chrome also uses WebKit and behaves the same way). The bug has been fixed in the current version of WebKit, so the next release of Safari and Chrome will probably fix it.
