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	$145.84	7.663%	$157.0157	$157.02	$157.00	$157.00
Purchase #2	$114.69	11.159%	$127.4883	$127.49	$127.50	$127.50
Purchase #3	$92.81	13.472%	$105.3134	$105.31	$105.30	$105.30
Purchase #4	$74.67	11.146%	$82.9927	$82.99	$83.00	$83.00
Purchase #5	$216.72	4.646%	$226.7888	$226.79	$226.80	$226.80
Purchase #6	$46.85	5.216%	$49.2937	$49.29	$49.30	$49.30
Purchase #7	$130.73	12.190%	$146.666	$146.67	$146.65	$146.70
7 purchase totals =	$822.31		$895.5586	$895.56	$895.55	$895.60