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	$193.61	10.569%	$214.0726	$214.07	$214.05	$214.10
Purchase #2	$173.88	6.585%	$185.33	$185.33	$185.35	$185.30
Purchase #3	$20.72	13.369%	$23.4901	$23.49	$23.50	$23.50
Purchase #4	$224.89	13.825%	$255.981	$255.98	$256.00	$256.00
Purchase #5	$111.51	6.615%	$118.8864	$118.89	$118.90	$118.90
Purchase #6	$53.82	11.745%	$60.1412	$60.14	$60.15	$60.10
Purchase #7	$204.98	10.102%	$225.6871	$225.69	$225.70	$225.70
7 purchase totals =	$983.41		$1,083.5884	$1,083.59	$1,083.65	$1,083.60