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	$89.49	6.196%	$95.0348	$95.03	$95.05	$95.00
Purchase #2	$120.45	5.770%	$127.4	$127.40	$127.40	$127.40
Purchase #3	$167.55	13.470%	$190.119	$190.12	$190.10	$190.10
Purchase #4	$88.49	13.784%	$100.6875	$100.69	$100.70	$100.70
Purchase #5	$212.93	6.669%	$227.1303	$227.13	$227.15	$227.10
Purchase #6	$94.80	7.451%	$101.8635	$101.86	$101.85	$101.90
Purchase #7	$245.91	10.358%	$271.3814	$271.38	$271.40	$271.40
7 purchase totals =	$1,019.62		$1,113.6165	$1,113.61	$1,113.65	$1,113.60