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	$171.25	13.668%	$194.6565	$194.66	$194.65	$194.70
Purchase #2	$99.28	3.265%	$102.5215	$102.52	$102.50	$102.50
Purchase #3	$9.77	5.202%	$10.2782	$10.28	$10.30	$10.30
Purchase #4	$99.36	12.245%	$111.5266	$111.53	$111.55	$111.50
Purchase #5	$145.40	5.285%	$153.0844	$153.08	$153.10	$153.10
Purchase #6	$162.44	8.653%	$176.4959	$176.50	$176.50	$176.50
Purchase #7	$177.68	7.838%	$191.6066	$191.61	$191.60	$191.60
7 purchase totals =	$865.18		$940.1697	$940.18	$940.20	$940.20