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	$102.52	8.459%	$111.1922	$111.19	$111.20	$111.20
Purchase #2	$12.33	11.777%	$13.7821	$13.78	$13.80	$13.80
Purchase #3	$148.25	12.707%	$167.0881	$167.09	$167.10	$167.10
Purchase #4	$183.33	13.502%	$208.0832	$208.08	$208.10	$208.10
Purchase #5	$88.84	7.612%	$95.6025	$95.60	$95.60	$95.60
Purchase #6	$230.68	12.300%	$259.0536	$259.05	$259.05	$259.10
Purchase #7	$147.26	12.129%	$165.1212	$165.12	$165.10	$165.10
7 purchase totals =	$913.21		$1,019.9229	$1,019.91	$1,019.95	$1,020.00