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	$151.70	10.485%	$167.6057	$167.61	$167.60	$167.60
Purchase #2	$64.91	11.152%	$72.1488	$72.15	$72.15	$72.10
Purchase #3	$154.96	3.171%	$159.8738	$159.87	$159.85	$159.90
Purchase #4	$227.79	10.717%	$252.2023	$252.20	$252.20	$252.20
Purchase #5	$175.31	11.516%	$195.4987	$195.50	$195.50	$195.50
Purchase #6	$12.84	13.234%	$14.5392	$14.54	$14.55	$14.50
Purchase #7	$140.72	9.781%	$154.4838	$154.48	$154.50	$154.50
7 purchase totals =	$928.23		$1,016.3523	$1,016.35	$1,016.35	$1,016.30