Had I been inclined to doubt Roberta's position on this subject (perish the thought), my doubts would have been put to rest by the review, in this week's New Yorker, of the new (15th) edition of the Chicago Manual of Style. The review says of the Manual:
"The authors are straightforward on two matters that many students are apparently hardwired at birth to find mindboggling: whether periods and commas belong inside or outside quotation marks, and whether inverted commas (sometimes called "single quotation marks") are an appropriate way to indicate an "ironic" usage. (Inside and no.)"
The review, which was written by Louis Menand, is brilliantly funny and deserves to be read in full. It's in the October 6 issue of the New Yorker, and can also be found online at:
New Yorker review of the Chicago Manual of Style