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	$212.76	5.731%	$224.9533	$224.95	$224.95	$225.00
Purchase #2	$108.67	3.302%	$112.2583	$112.26	$112.25	$112.30
Purchase #3	$59.42	3.388%	$61.4331	$61.43	$61.45	$61.40
Purchase #4	$126.29	12.136%	$141.6166	$141.62	$141.60	$141.60
Purchase #5	$117.77	4.133%	$122.6374	$122.64	$122.65	$122.60
Purchase #6	$213.61	4.175%	$222.5282	$222.53	$222.55	$222.50
Purchase #7	$18.39	10.313%	$20.2866	$20.29	$20.30	$20.30
7 purchase totals =	$856.91		$905.7135	$905.72	$905.75	$905.70