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	$233.60	4.488%	$244.084	$244.08	$244.10	$244.10
Purchase #2	$179.95	9.259%	$196.6116	$196.61	$196.60	$196.60
Purchase #3	$237.40	3.682%	$246.1411	$246.14	$246.15	$246.10
Purchase #4	$219.59	11.363%	$244.542	$244.54	$244.55	$244.50
Purchase #5	$57.44	5.864%	$60.8083	$60.81	$60.80	$60.80
Purchase #6	$32.60	9.580%	$35.7231	$35.72	$35.70	$35.70
Purchase #7	$62.71	6.237%	$66.6212	$66.62	$66.60	$66.60
7 purchase totals =	$1,023.29		$1,094.5313	$1,094.52	$1,094.50	$1,094.40