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	$82.92	10.539%	$91.6589	$91.66	$91.65	$91.70
Purchase #2	$18.95	12.554%	$21.329	$21.33	$21.35	$21.30
Purchase #3	$172.79	3.158%	$178.2467	$178.25	$178.25	$178.20
Purchase #4	$119.39	12.615%	$134.451	$134.45	$134.45	$134.50
Purchase #5	$80.43	11.732%	$89.866	$89.87	$89.85	$89.90
Purchase #6	$12.79	9.422%	$13.9951	$14.00	$14.00	$14.00
Purchase #7	$207.38	12.433%	$233.1636	$233.16	$233.15	$233.20
7 purchase totals =	$694.65		$762.7103	$762.72	$762.70	$762.80