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	$100.59	4.448%	$105.0642	$105.06	$105.05	$105.10
Purchase #2	$57.55	7.536%	$61.887	$61.89	$61.90	$61.90
Purchase #3	$140.91	6.577%	$150.1777	$150.18	$150.20	$150.20
Purchase #4	$140.44	13.434%	$159.3067	$159.31	$159.30	$159.30
Purchase #5	$43.42	13.613%	$49.3308	$49.33	$49.35	$49.30
Purchase #6	$76.49	4.178%	$79.6858	$79.69	$79.70	$79.70
Purchase #7	$235.55	11.514%	$262.6712	$262.67	$262.65	$262.70
7 purchase totals =	$794.95		$868.1234	$868.13	$868.15	$868.20