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	$188.68	11.717%	$210.7876	$210.79	$210.80	$210.80
Purchase #2	$233.97	3.804%	$242.8702	$242.87	$242.85	$242.90
Purchase #3	$67.66	5.792%	$71.5789	$71.58	$71.60	$71.60
Purchase #4	$97.27	6.144%	$103.2463	$103.25	$103.25	$103.20
Purchase #5	$48.85	12.342%	$54.8791	$54.88	$54.90	$54.90
Purchase #6	$80.45	10.708%	$89.0646	$89.06	$89.05	$89.10
Purchase #7	$216.65	11.695%	$241.9872	$241.99	$242.00	$242.00
7 purchase totals =	$933.53		$1,014.4139	$1,014.42	$1,014.45	$1,014.50