For various reasons, we often have a constituent give more than one gift in a day - especially online (if they give multiple tribute gifts, or gifts to different funds) - and we want a sum total on their acknowledgment letter. Currently, we have to total them manually, which takes a lot of extra time and leaves room for error.
If you are receipting constituents you may want to consider changing from acknowledging gifts to receipting in RE. Consolidated receipt function give you a total amount. :)
You can also do a consolidated acknowledgement in RE. You will lose some of the detail you can get with individual gift acknowledgements (such as fund, etc.) but this is already possible if you use the Mail functionality.
If you do not know how to do this - go to tab 2: Fields to include and change the top option from per gift to per donor.