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	$44.80	3.797%	$46.5011	$46.50	$46.50	$46.50
Purchase #2	$13.82	7.733%	$14.8887	$14.89	$14.90	$14.90
Purchase #3	$219.32	10.176%	$241.638	$241.64	$241.65	$241.60
Purchase #4	$98.63	13.425%	$111.8711	$111.87	$111.85	$111.90
Purchase #5	$202.43	5.117%	$212.7883	$212.79	$212.80	$212.80
Purchase #6	$190.65	5.184%	$200.5333	$200.53	$200.55	$200.50
Purchase #7	$205.80	3.580%	$213.1676	$213.17	$213.15	$213.20
7 purchase totals =	$975.45		$1,041.3881	$1,041.39	$1,041.40	$1,041.40