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	$219.29	6.576%	$233.7105	$233.71	$233.70	$233.70
Purchase #2	$50.64	7.489%	$54.4324	$54.43	$54.45	$54.40
Purchase #3	$159.47	3.684%	$165.3449	$165.34	$165.35	$165.30
Purchase #4	$217.44	13.776%	$247.3945	$247.39	$247.40	$247.40
Purchase #5	$211.89	6.429%	$225.5124	$225.51	$225.50	$225.50
Purchase #6	$67.36	7.846%	$72.6451	$72.65	$72.65	$72.60
Purchase #7	$154.34	8.225%	$167.0345	$167.03	$167.05	$167.00
7 purchase totals =	$1,080.43		$1,166.0743	$1,166.06	$1,166.10	$1,165.90