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	$109.49	4.544%	$114.4652	$114.47	$114.45	$114.50
Purchase #2	$243.34	7.871%	$262.4933	$262.49	$262.50	$262.50
Purchase #3	$117.34	4.767%	$122.9336	$122.93	$122.95	$122.90
Purchase #4	$162.86	10.610%	$180.1394	$180.14	$180.15	$180.10
Purchase #5	$157.97	13.359%	$179.0732	$179.07	$179.05	$179.10
Purchase #6	$40.96	3.636%	$42.4493	$42.45	$42.45	$42.40
Purchase #7	$127.38	10.749%	$141.0721	$141.07	$141.05	$141.10
7 purchase totals =	$959.34		$1,042.6261	$1,042.62	$1,042.60	$1,042.60