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	$85.42	8.336%	$92.5406	$92.54	$92.55	$92.50
Purchase #2	$173.78	4.762%	$182.0554	$182.06	$182.05	$182.10
Purchase #3	$91.83	12.833%	$103.6145	$103.61	$103.60	$103.60
Purchase #4	$193.28	3.289%	$199.637	$199.64	$199.65	$199.60
Purchase #5	$102.35	8.490%	$111.0395	$111.04	$111.05	$111.00
Purchase #6	$161.27	9.711%	$176.9309	$176.93	$176.95	$176.90
Purchase #7	$191.50	13.116%	$216.6171	$216.62	$216.60	$216.60
7 purchase totals =	$999.43		$1,082.4350	$1,082.44	$1,082.45	$1,082.30