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	$186.73	7.615%	$200.9495	$200.95	$200.95	$200.90
Purchase #2	$52.32	6.494%	$55.7177	$55.72	$55.70	$55.70
Purchase #3	$55.83	13.814%	$63.5424	$63.54	$63.55	$63.50
Purchase #4	$200.31	9.756%	$219.8522	$219.85	$219.85	$219.90
Purchase #5	$139.75	10.773%	$154.8053	$154.81	$154.80	$154.80
Purchase #6	$105.81	12.197%	$118.7156	$118.72	$118.70	$118.70
Purchase #7	$50.75	5.495%	$53.5387	$53.54	$53.55	$53.50
7 purchase totals =	$791.50		$867.1214	$867.13	$867.10	$867.00