A lot. ;)
The answer will depend on pennies from which country!
50
12
Assuming that the 14 inch box is square, you could fit a circle inside with a 14 inch diameter.
91 with .79 cubic inches to spare.
1,728
729 of them!
1,000-3,000 pennies
60 - 70
50,000
Approximately 7,500 pennies could fit in a three gallon jug.
The answer will depend on the country whose pennies you have in mind. Since you have not shared that crucial bit of information, I cannot provide a more useful answer.