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	$182.58	7.597%	$196.4506	$196.45	$196.45	$196.50
Purchase #2	$198.67	7.668%	$213.904	$213.90	$213.90	$213.90
Purchase #3	$239.53	6.752%	$255.7031	$255.70	$255.70	$255.70
Purchase #4	$172.40	6.279%	$183.225	$183.23	$183.25	$183.20
Purchase #5	$220.26	11.356%	$245.2727	$245.27	$245.25	$245.30
Purchase #6	$100.60	5.107%	$105.7376	$105.74	$105.75	$105.70
Purchase #7	$105.46	10.409%	$116.4373	$116.44	$116.45	$116.40
7 purchase totals =	$1,219.50		$1,316.7303	$1,316.73	$1,316.75	$1,316.70