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	$48.45	4.465%	$50.6133	$50.61	$50.60	$50.60
Purchase #2	$113.95	11.103%	$126.6019	$126.60	$126.60	$126.60
Purchase #3	$103.31	7.779%	$111.3465	$111.35	$111.35	$111.30
Purchase #4	$206.64	10.564%	$228.4694	$228.47	$228.45	$228.50
Purchase #5	$248.71	11.426%	$277.1276	$277.13	$277.15	$277.10
Purchase #6	$215.70	7.411%	$231.6855	$231.69	$231.70	$231.70
Purchase #7	$34.83	11.648%	$38.887	$38.89	$38.90	$38.90
7 purchase totals =	$971.59		$1,064.7312	$1,064.74	$1,064.75	$1,064.70