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	$92.48	4.627%	$96.759	$96.76	$96.75	$96.80
Purchase #2	$179.37	11.653%	$200.272	$200.27	$200.25	$200.30
Purchase #3	$242.57	5.259%	$255.3268	$255.33	$255.35	$255.30
Purchase #4	$183.62	3.190%	$189.4775	$189.48	$189.50	$189.50
Purchase #5	$226.38	6.247%	$240.522	$240.52	$240.50	$240.50
Purchase #6	$32.48	3.277%	$33.5444	$33.54	$33.55	$33.50
Purchase #7	$56.58	10.804%	$62.6929	$62.69	$62.70	$62.70
7 purchase totals =	$1,013.48		$1,078.5946	$1,078.59	$1,078.60	$1,078.60