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	$217.70	4.568%	$227.6445	$227.64	$227.65	$227.60
Purchase #2	$248.53	7.254%	$266.5584	$266.56	$266.55	$266.60
Purchase #3	$62.25	13.552%	$70.6861	$70.69	$70.70	$70.70
Purchase #4	$248.89	7.492%	$267.5368	$267.54	$267.55	$267.50
Purchase #5	$223.38	8.722%	$242.8632	$242.86	$242.85	$242.90
Purchase #6	$68.73	9.773%	$75.447	$75.45	$75.45	$75.40
Purchase #7	$67.71	6.110%	$71.8471	$71.85	$71.85	$71.80
7 purchase totals =	$1,137.19		$1,222.5831	$1,222.59	$1,222.60	$1,222.50