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	$200.52	11.178%	$222.9341	$222.93	$222.95	$222.90
Purchase #2	$200.66	11.393%	$223.5212	$223.52	$223.50	$223.50
Purchase #3	$143.76	10.290%	$158.5529	$158.55	$158.55	$158.60
Purchase #4	$224.30	3.121%	$231.3004	$231.30	$231.30	$231.30
Purchase #5	$100.88	10.535%	$111.5077	$111.51	$111.50	$111.50
Purchase #6	$89.83	7.316%	$96.402	$96.40	$96.40	$96.40
Purchase #7	$149.48	4.685%	$156.4831	$156.48	$156.50	$156.50
7 purchase totals =	$1,109.43		$1,200.7014	$1,200.69	$1,200.70	$1,200.70