Grammatically Correct: The writer's essential guide to punctuation ...

GRAMMATICALLY CORRECT
DON'T INCLUDE A PERIOD IF A SENTENCE ENDS IN ANOTHER
TERMINAL PUNCTUATION MARK, EVEN IF THAT MARK
DOES NOT APPLY TO THE SENTENCE ASA WHOLE
They signed their divorce papers right after lunch, and then headed off
to a matinee of I Do! I Do!
Before you begin, be sure to read the section entitled Should I Begin?
She has that annoying habit of ending almost every sentence with "you
know what I mean?"
Readers will understand that in cases like this the question mark
or exclamation point applies to just the words at the end, and that
the entire sentence is not querying or exclamatory.
Note that if the words for which the other punctuation mark
applies are enclosed within parentheses, you would put a period at
the end of the sentence. See the section on style conventions under
"Parentheses" on page 150.
IF A SENTENCE ENDS IN AN ABBREVIATION THAT INCLUDES
A PERIOD, DO NOT ADD ANOTHER PERIOD
If you have any complaints about this product, send them in writing to
Acme Manufacturing, Inc.
The list of student demands included less homework, a better selection
of ice cream flavors in the cafeteria, more time allotted for surfing the
Net, etc.
That is, you let the period that goes with the abbreviation do
double duty as a terminal punctuation mark.
Note: You may follow an abbreviating period at the end of a
sentence with a question mark or exclamation point. For example:
Is the company name followed by Inc. or Ltd.?
BE CONSISTENT WITH THE USE OF PERIODS
AT THE END OF LIST ITEMS
Style guides differ as to whether a period should appear at the end of
each item in a vertical list. That is, should your list be presented as:
108
Item 1.
Item 2.
Item 3.
OR Item 1
Item 2
Item 3