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	$196.96	4.242%	$205.315	$205.32	$205.30	$205.30
Purchase #2	$214.67	6.512%	$228.6493	$228.65	$228.65	$228.60
Purchase #3	$11.95	5.633%	$12.6231	$12.62	$12.60	$12.60
Purchase #4	$41.78	8.662%	$45.399	$45.40	$45.40	$45.40
Purchase #5	$161.64	13.429%	$183.3466	$183.35	$183.35	$183.30
Purchase #6	$235.52	13.171%	$266.5403	$266.54	$266.55	$266.50
Purchase #7	$203.40	9.771%	$223.2742	$223.27	$223.25	$223.30
7 purchase totals =	$1,065.92		$1,165.1475	$1,165.15	$1,165.10	$1,165.00