1.  Create a Gift query.
2.  On the Criteria tab, select Gift date between [x] - [x].
3.  Save and Close the query.
4.  Create a Gift Export in CSV or Excel format.
5.  On the General tab, click Include, choose selected records and select the query created above.  
6.  On the Output tab, select Receipt amount.
7.  Click Export now and save the document.
8.  Open the document and use the SUM feature in Excel to get a total receipt amount.