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	$103.67	7.717%	$111.6702	$111.67	$111.65	$111.70
Purchase #2	$188.40	7.434%	$202.4057	$202.41	$202.40	$202.40
Purchase #3	$61.61	7.694%	$66.3503	$66.35	$66.35	$66.40
Purchase #4	$54.30	4.792%	$56.9021	$56.90	$56.90	$56.90
Purchase #5	$203.87	6.265%	$216.6425	$216.64	$216.65	$216.60
Purchase #6	$233.27	11.544%	$260.1987	$260.20	$260.20	$260.20
Purchase #7	$157.76	13.736%	$179.4299	$179.43	$179.45	$179.40
7 purchase totals =	$1,002.88		$1,093.5994	$1,093.60	$1,093.60	$1,093.60