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	$55.49	5.528%	$58.5575	$58.56	$58.55	$58.60
Purchase #2	$177.25	4.742%	$185.6552	$185.66	$185.65	$185.70
Purchase #3	$86.32	12.482%	$97.0945	$97.09	$97.10	$97.10
Purchase #4	$210.32	6.255%	$223.4755	$223.48	$223.50	$223.50
Purchase #5	$228.86	13.853%	$260.564	$260.56	$260.55	$260.60
Purchase #6	$224.38	9.852%	$246.4859	$246.49	$246.50	$246.50
Purchase #7	$95.51	5.411%	$100.678	$100.68	$100.70	$100.70
7 purchase totals =	$1,078.13		$1,172.5106	$1,172.52	$1,172.55	$1,172.70