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	$191.67	8.675%	$208.2974	$208.30	$208.30	$208.30
Purchase #2	$70.54	8.433%	$76.4886	$76.49	$76.50	$76.50
Purchase #3	$10.58	12.689%	$11.9225	$11.92	$11.90	$11.90
Purchase #4	$200.34	7.176%	$214.7164	$214.72	$214.70	$214.70
Purchase #5	$223.92	9.613%	$245.4454	$245.45	$245.45	$245.40
Purchase #6	$143.25	6.152%	$152.0627	$152.06	$152.05	$152.10
Purchase #7	$132.58	6.586%	$141.3117	$141.31	$141.30	$141.30
7 purchase totals =	$972.88		$1,050.2447	$1,050.25	$1,050.20	$1,050.20