The hazards of rounding

I parked at a meter today where the rate was 8 minutes per 25 cents. I threw in a nickel and the meter added 1 minute. I inserted in a dime and got and an additional 3 minutes. The meter was rounding down and not even correctly. My 5 cent piece should have netted me 96 seconds and my 10 cent piece 192 seconds. Instead, one quarter, four dimes and three nickels only got me 23 minutes, where I should have received 25 and a half minutes. I believe not accepting all forms of money at face value is a Federal offense. I certainly was offended.