All sacrifices are meant for achieving the Supreme Lord. Therefore, charity is for the purification of the heart. If charity is given to suitable persons as described in the Bhagavad-gita, it leads one to advanced spiritual life.
"If anyone is charitably disposed, it will be very good for Him to give charity only to Krishna... Krishna is present as the Supersoul in every living being, and if we can satisfy Him, then every living being will automatically be satisfied." (Srila Prabhupada's Krishna Book, Chapter 74.)
"All benedictions are given by the Lord. If one gives something in charity to the Lord he can't be a loser, only a winner a million times." (Krishna Book, Chapter 11.)