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	$104.27	11.325%	$116.0786	$116.08	$116.10	$116.10
Purchase #2	$153.98	11.737%	$172.0526	$172.05	$172.05	$172.10
Purchase #3	$248.63	6.821%	$265.5891	$265.59	$265.60	$265.60
Purchase #4	$55.34	3.555%	$57.3073	$57.31	$57.30	$57.30
Purchase #5	$12.80	6.841%	$13.6756	$13.68	$13.70	$13.70
Purchase #6	$167.51	12.120%	$187.8122	$187.81	$187.80	$187.80
Purchase #7	$229.59	12.684%	$258.7112	$258.71	$258.70	$258.70
7 purchase totals =	$972.12		$1,071.2266	$1,071.23	$1,071.25	$1,071.30