LED 7 will count up, but will only show the time increase in seconds / minutes.
LED 6 can show either the time increase, or the $ increase in $.01 increments.
The customer will not know "how much $" they spent until the stop button is pushed with the LED 7. Only then does the timer reveal the $ amount spent.
With the LED 6, the customer can see the $ amount they are at when they look at the timer as it is counting up.