I don't know how to make it affect every text object in my doc (or every selected text object).
// rounds the size of text in all textFrames in your document
var aTFrame = app.activeDocument.textFrames;
for ( i = 0; i < aTFrame.length; i++ )
{
var fractionSize = aTFrame.textRange.characterAttributes.size;
var RoundedSize = Math.round(fractionSize);
aTFrame.textRange.characterAttributes.size = RoundedSize;
}
redraw();
This will do all the text frames. Copy the above, paste it into a text editor or the Adobe ESTK (ExtendScript Tool Kit) and save as a plain text file with a .jsx extension. Place it into Applications/Adobe Illustrator CSX/Presets/en_US/Scripts folder and restart AI. Run it by having a document open in AI and call it from File>Scripts>scriptname.