Don't worry about it! Most bettas wont eat for a few days after you get them, it just means he's settling in. It could take anything from a few days to a week. It's normal, so don't stress over it! :) Also, 76F is a bit chilly for bettas, I would boost it to 78F. The safe range for bettas is 77-82F. Warmer temperatures keep their appetite up! My bettas are all at 80F and eating well. :)
Seriously, don't panic, bettas can live for weeks without food :) Just keep trying in a couple days, and whatever food he doesnt eat, remove from the tank so it does not foul up the water.