Never underestimate

In the days when an ice cream sundae cost much less, a 10 year old boy entered a hotel coffee shop and sat at a table. A waitress put a glass of water in front of him.
"How much is an ice cream sundae?"
"Fifty cents," replied the waitress.
The little boy pulled his hand out of his pocket and studied the number of coins in it.
"How much is a dish of plain ice cream?" he inquired.
Some people were now waiting for a table and the waitress was a bit impatient.
"Thirty-five cents," she said brusquely.
The little boy again counted the coins.
"I'll have the plain ice cream," he said.
The waitress brought the ice cream, put the bill on the table and walked away. The boy finished the ice cream, paid the cashier and departed.
When the waitress came back, she began wiping down the table and then swallowed hard at what she saw. There, placed neatly beside the empty dish, were two nickels and five pennies - her tip