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	$185.38	8.352%	$200.8629	$200.86	$200.85	$200.90
Purchase #2	$101.63	10.325%	$112.1233	$112.12	$112.10	$112.10
Purchase #3	$220.40	4.482%	$230.2783	$230.28	$230.30	$230.30
Purchase #4	$39.43	13.213%	$44.6399	$44.64	$44.65	$44.60
Purchase #5	$203.83	11.384%	$227.034	$227.03	$227.05	$227.00
Purchase #6	$234.61	4.784%	$245.8337	$245.83	$245.85	$245.80
Purchase #7	$12.60	9.194%	$13.7584	$13.76	$13.75	$13.80
7 purchase totals =	$997.88		$1,074.5305	$1,074.52	$1,074.55	$1,074.50