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	$208.39	5.837%	$220.5537	$220.55	$220.55	$220.60
Purchase #2	$38.51	4.195%	$40.1255	$40.13	$40.15	$40.10
Purchase #3	$155.65	7.672%	$167.5915	$167.59	$167.60	$167.60
Purchase #4	$76.84	7.185%	$82.361	$82.36	$82.35	$82.40
Purchase #5	$224.76	6.191%	$238.6749	$238.67	$238.65	$238.70
Purchase #6	$137.60	8.846%	$149.7721	$149.77	$149.75	$149.80
Purchase #7	$234.70	7.313%	$251.8636	$251.86	$251.85	$251.90
7 purchase totals =	$1,076.45		$1,150.9423	$1,150.93	$1,150.90	$1,151.10