Well, if the pinwheels cost $1 each, then 10 dimes is what it would take to pay for them. 10 dimes = 1 dollar, because a dime has a value of 10 cents and 10 times 10 = 100, and there is 100 cents in a dollar.
If you round each amount to the nearest ten you get $130.00, $60.00, and 50.00. When you add all of those together you get an estimated amount of $240.
