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	$181.87	7.663%	$195.8067	$195.81	$195.80	$195.80
Purchase #2	$243.53	10.522%	$269.1542	$269.15	$269.15	$269.20
Purchase #3	$143.52	4.856%	$150.4893	$150.49	$150.50	$150.50
Purchase #4	$117.65	4.452%	$122.8878	$122.89	$122.90	$122.90
Purchase #5	$199.29	11.168%	$221.5467	$221.55	$221.55	$221.50
Purchase #6	$97.64	5.662%	$103.1684	$103.17	$103.15	$103.20
Purchase #7	$83.71	8.492%	$90.8187	$90.82	$90.80	$90.80
7 purchase totals =	$1,067.21		$1,153.8718	$1,153.88	$1,153.85	$1,153.90