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	$176.42	13.598%	$200.4096	$200.41	$200.40	$200.40
Purchase #2	$90.51	9.255%	$98.8867	$98.89	$98.90	$98.90
Purchase #3	$247.46	3.485%	$256.084	$256.08	$256.10	$256.10
Purchase #4	$46.26	9.106%	$50.4724	$50.47	$50.45	$50.50
Purchase #5	$117.87	13.154%	$133.3746	$133.37	$133.35	$133.40
Purchase #6	$98.94	12.411%	$111.2194	$111.22	$111.20	$111.20
Purchase #7	$175.49	4.363%	$183.1466	$183.15	$183.15	$183.10
7 purchase totals =	$952.95		$1,033.5933	$1,033.59	$1,033.55	$1,033.60