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	$100.92	4.716%	$105.6794	$105.68	$105.70	$105.70
Purchase #2	$105.84	6.451%	$112.6677	$112.67	$112.65	$112.70
Purchase #3	$20.57	3.601%	$21.3107	$21.31	$21.30	$21.30
Purchase #4	$90.43	10.492%	$99.9179	$99.92	$99.90	$99.90
Purchase #5	$42.98	8.159%	$46.4867	$46.49	$46.50	$46.50
Purchase #6	$47.91	11.711%	$53.5207	$53.52	$53.50	$53.50
Purchase #7	$28.27	3.209%	$29.1772	$29.18	$29.20	$29.20
7 purchase totals =	$436.92		$468.7603	$468.77	$468.75	$468.80