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	$119.71	8.845%	$130.2983	$130.30	$130.30	$130.30
Purchase #2	$144.69	4.610%	$151.3602	$151.36	$151.35	$151.40
Purchase #3	$91.58	3.316%	$94.6168	$94.62	$94.60	$94.60
Purchase #4	$207.35	7.500%	$222.9013	$222.90	$222.90	$222.90
Purchase #5	$81.72	11.242%	$90.907	$90.91	$90.90	$90.90
Purchase #6	$109.50	6.611%	$116.739	$116.74	$116.75	$116.70
Purchase #7	$192.67	4.472%	$201.2862	$201.29	$201.30	$201.30
7 purchase totals =	$947.22		$1,008.1088	$1,008.12	$1,008.10	$1,008.10