Yes.. not only that, Smiling is a form of giving and generosity.

When we give others a smile, it
is also a form of giving. This is indeed a very simple thing to do,
which does not cost time and money! And, when others reciprocate,
it is such a comfortable thing! - Ven Shen Kai
Generosity is very wide and vast, a smile is a simple act of
giving, a good start to practise Generosity. 