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	$222.88	8.734%	$242.3463	$242.35	$242.35	$242.30
Purchase #2	$239.74	13.400%	$271.8652	$271.87	$271.85	$271.90
Purchase #3	$114.81	7.508%	$123.4299	$123.43	$123.45	$123.40
Purchase #4	$11.81	8.435%	$12.8062	$12.81	$12.80	$12.80
Purchase #5	$33.46	12.773%	$37.7338	$37.73	$37.75	$37.70
Purchase #6	$140.94	13.394%	$159.8175	$159.82	$159.80	$159.80
Purchase #7	$183.98	6.785%	$196.463	$196.46	$196.45	$196.50
7 purchase totals =	$947.62		$1,044.4619	$1,044.47	$1,044.45	$1,044.40