So, in returning somewhat to my charter, I want to point out (without naming names, Jake Freivald) that one should try to pick a side and be consistent.
That is, if you want to write like a Brit, I'm sure there's room for you across the pond. But as an American communication professional, I recommend adherence to an American style guide. You don't even need to pick one style guide. I mean, I float freely among AP, Chicago, AMA, or even the corporate style guide du jour - that is, I happily flex to please my clients. And when writing fiction, I stick with Generally Accepted American English (GAAE). Yes, I made that up. And, of course, there are exceptions for accented dialogue, poetry, etc.
So, why do I bring this up? Because when you are writing in the United States, for a mostly American audience, your commas and periods belong inside the quotation marks. This is not a matter of personal preference.
"That is all."
