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	$116.58	9.662%	$127.844	$127.84	$127.85	$127.80
Purchase #2	$27.97	3.220%	$28.8706	$28.87	$28.85	$28.90
Purchase #3	$49.63	8.275%	$53.7369	$53.74	$53.75	$53.70
Purchase #4	$90.81	8.858%	$98.8539	$98.85	$98.85	$98.90
Purchase #5	$203.79	5.175%	$214.3361	$214.34	$214.35	$214.30
Purchase #6	$101.27	10.123%	$111.5216	$111.52	$111.50	$111.50
Purchase #7	$44.77	10.546%	$49.4914	$49.49	$49.50	$49.50
7 purchase totals =	$634.82		$684.6545	$684.65	$684.65	$684.60