sum amounts in one column based on dates in another column

How do I scan through column A to find all the entries from a particular month (ie. Dec or Jan, etc) and then sum the corresponding dollar amounts in column C?

A B C
12/15/2010 Div of Revenue License $75.00
12/16/2010 DE Bus. License $190.00
12/21/2010 Opening Bank Account $500.00
1/19/2011 software MS Office 2011 $119.99
1/19/2011 printer/fax/copier $99.99

Hi Mark,

Find the attached with two methods.