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	$162.37	4.186%	$169.1668	$169.17	$169.15	$169.20
Purchase #2	$12.74	5.761%	$13.474	$13.47	$13.45	$13.50
Purchase #3	$183.59	8.161%	$198.5728	$198.57	$198.55	$198.60
Purchase #4	$198.89	9.409%	$217.6036	$217.60	$217.60	$217.60
Purchase #5	$73.65	3.779%	$76.4332	$76.43	$76.45	$76.40
Purchase #6	$238.91	13.814%	$271.913	$271.91	$271.90	$271.90
Purchase #7	$89.86	11.388%	$100.0933	$100.09	$100.10	$100.10
7 purchase totals =	$960.01		$1,047.2567	$1,047.24	$1,047.20	$1,047.30