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	$94.60	11.642%	$105.6133	$105.61	$105.60	$105.60
Purchase #2	$193.88	10.265%	$213.7818	$213.78	$213.80	$213.80
Purchase #3	$69.63	6.513%	$74.165	$74.17	$74.15	$74.20
Purchase #4	$216.75	4.313%	$226.0984	$226.10	$226.10	$226.10
Purchase #5	$48.89	4.480%	$51.0803	$51.08	$51.10	$51.10
Purchase #6	$240.64	6.546%	$256.3923	$256.39	$256.40	$256.40
Purchase #7	$83.47	8.627%	$90.671	$90.67	$90.65	$90.70
7 purchase totals =	$947.86		$1,017.8021	$1,017.80	$1,017.80	$1,017.90