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	$117.48	7.468%	$126.2534	$126.25	$126.25	$126.30
Purchase #2	$78.83	8.679%	$85.6717	$85.67	$85.65	$85.70
Purchase #3	$92.41	8.849%	$100.5874	$100.59	$100.60	$100.60
Purchase #4	$198.50	4.823%	$208.0737	$208.07	$208.05	$208.10
Purchase #5	$38.87	13.856%	$44.2558	$44.26	$44.25	$44.30
Purchase #6	$236.40	7.599%	$254.364	$254.36	$254.35	$254.40
Purchase #7	$245.48	8.505%	$266.3581	$266.36	$266.35	$266.40
7 purchase totals =	$1,007.97		$1,085.5641	$1,085.56	$1,085.50	$1,085.80