Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$218.29	4.434%	$227.969	$227.97	$227.95	$228.00
Purchase #2	$183.89	13.360%	$208.4577	$208.46	$208.45	$208.50
Purchase #3	$102.83	11.724%	$114.8858	$114.89	$114.90	$114.90
Purchase #4	$203.53	5.714%	$215.1597	$215.16	$215.15	$215.20
Purchase #5	$91.51	4.311%	$95.455	$95.46	$95.45	$95.50
Purchase #6	$134.32	12.335%	$150.8884	$150.89	$150.90	$150.90
Purchase #7	$116.63	12.337%	$131.0186	$131.02	$131.00	$131.00
7 purchase totals =	$1,051.00		$1,143.8342	$1,143.85	$1,143.80	$1,144.00