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	$58.34	5.771%	$61.7068	$61.71	$61.70	$61.70
Purchase #2	$111.94	4.407%	$116.8732	$116.87	$116.85	$116.90
Purchase #3	$114.71	6.798%	$122.508	$122.51	$122.50	$122.50
Purchase #4	$156.29	5.388%	$164.7109	$164.71	$164.70	$164.70
Purchase #5	$51.45	13.873%	$58.5877	$58.59	$58.60	$58.60
Purchase #6	$223.34	4.727%	$233.8973	$233.90	$233.90	$233.90
Purchase #7	$247.86	6.696%	$264.4567	$264.46	$264.45	$264.50
7 purchase totals =	$963.93		$1,022.7406	$1,022.75	$1,022.70	$1,022.80