A 12 oz can of beer is 12 by 6 cm. Judging by the photo, the jar is about twice as wide and a bit taller (say 1.5 times) than the can (at the point where the coins are).. That means the radius of the cylinder is 6 cm, so pi x (36) = 113 times the height (18) = 2000 cubic centimeters, or two liters.
A penny has a volume of .36 cubic centimeters. Assuming perfect fit, this would equal about 5550 pennies or $55.50 . A pretty liberal estimate is that only 80% of the space is used, which would equal $44.40. That would be the absolute least. (and a lot of people have guessed below it!
)
But we know for sure there are other coins!
I'm going to guess $140 for reasons that are too illogical to get into now.