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	$177.41	10.400%	$195.8606	$195.86	$195.85	$195.90
Purchase #2	$149.42	8.428%	$162.0131	$162.01	$162.00	$162.00
Purchase #3	$78.29	10.602%	$86.5903	$86.59	$86.60	$86.60
Purchase #4	$146.30	5.794%	$154.7766	$154.78	$154.80	$154.80
Purchase #5	$111.41	12.673%	$125.529	$125.53	$125.55	$125.50
Purchase #6	$58.76	12.547%	$66.1326	$66.13	$66.15	$66.10
Purchase #7	$104.76	6.560%	$111.6323	$111.63	$111.65	$111.60
7 purchase totals =	$826.35		$902.5345	$902.53	$902.60	$902.50