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	$111.25	7.260%	$119.3268	$119.33	$119.35	$119.30
Purchase #2	$13.62	3.564%	$14.1054	$14.11	$14.10	$14.10
Purchase #3	$12.90	4.815%	$13.5211	$13.52	$13.50	$13.50
Purchase #4	$119.84	6.522%	$127.656	$127.66	$127.65	$127.70
Purchase #5	$18.93	11.615%	$21.1287	$21.13	$21.15	$21.10
Purchase #6	$32.60	5.625%	$34.4338	$34.43	$34.45	$34.40
Purchase #7	$126.74	5.301%	$133.4585	$133.46	$133.45	$133.50
7 purchase totals =	$435.88		$463.6303	$463.64	$463.65	$463.60