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	$169.30	8.705%	$184.0376	$184.04	$184.05	$184.00
Purchase #2	$249.33	6.863%	$266.4415	$266.44	$266.45	$266.40
Purchase #3	$151.49	13.609%	$172.1063	$172.11	$172.10	$172.10
Purchase #4	$116.46	13.711%	$132.4278	$132.43	$132.45	$132.40
Purchase #5	$172.29	3.683%	$178.6354	$178.64	$178.65	$178.60
Purchase #6	$11.79	10.867%	$13.0712	$13.07	$13.05	$13.10
Purchase #7	$149.32	13.573%	$169.5872	$169.59	$169.60	$169.60
7 purchase totals =	$1,019.98		$1,116.3070	$1,116.32	$1,116.35	$1,116.20