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	$43.34	5.761%	$45.8368	$45.84	$45.85	$45.80
Purchase #2	$228.76	5.731%	$241.8702	$241.87	$241.85	$241.90
Purchase #3	$116.52	11.414%	$129.8196	$129.82	$129.80	$129.80
Purchase #4	$137.82	5.466%	$145.3532	$145.35	$145.35	$145.40
Purchase #5	$159.32	5.742%	$168.4682	$168.47	$168.45	$168.50
Purchase #6	$94.43	6.576%	$100.6397	$100.64	$100.65	$100.60
Purchase #7	$200.94	13.292%	$227.6489	$227.65	$227.65	$227.60
7 purchase totals =	$981.13		$1,059.6366	$1,059.64	$1,059.60	$1,059.60