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	$214.29	7.482%	$230.3232	$230.32	$230.30	$230.30
Purchase #2	$153.27	9.315%	$167.5471	$167.55	$167.55	$167.50
Purchase #3	$111.33	13.570%	$126.4375	$126.44	$126.45	$126.40
Purchase #4	$173.72	6.437%	$184.9024	$184.90	$184.90	$184.90
Purchase #5	$54.78	3.480%	$56.6863	$56.69	$56.70	$56.70
Purchase #6	$68.74	4.298%	$71.6944	$71.69	$71.70	$71.70
Purchase #7	$231.30	12.248%	$259.6296	$259.63	$259.65	$259.60
7 purchase totals =	$1,007.43		$1,097.2205	$1,097.22	$1,097.25	$1,097.10