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	$95.76	5.785%	$101.2997	$101.30	$101.30	$101.30
Purchase #2	$178.56	4.634%	$186.8345	$186.83	$186.85	$186.80
Purchase #3	$50.83	6.782%	$54.2773	$54.28	$54.30	$54.30
Purchase #4	$164.33	11.833%	$183.7752	$183.78	$183.80	$183.80
Purchase #5	$173.68	10.113%	$191.2443	$191.24	$191.25	$191.20
Purchase #6	$106.25	4.208%	$110.721	$110.72	$110.70	$110.70
Purchase #7	$177.42	4.725%	$185.8031	$185.80	$185.80	$185.80
7 purchase totals =	$946.83		$1,013.9551	$1,013.95	$1,014.00	$1,013.90