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	$13.25	7.575%	$14.2537	$14.25	$14.25	$14.30
Purchase #2	$144.82	4.359%	$151.1327	$151.13	$151.15	$151.10
Purchase #3	$69.94	3.655%	$72.4963	$72.50	$72.50	$72.50
Purchase #4	$100.60	10.669%	$111.333	$111.33	$111.35	$111.30
Purchase #5	$34.67	12.181%	$38.8932	$38.89	$38.90	$38.90
Purchase #6	$170.68	11.563%	$190.4157	$190.42	$190.40	$190.40
Purchase #7	$190.92	3.424%	$197.4571	$197.46	$197.45	$197.50
7 purchase totals =	$724.88		$775.9817	$775.98	$776.00	$776.00