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	$119.49	11.233%	$132.9123	$132.91	$132.90	$132.90
Purchase #2	$34.52	11.114%	$38.3566	$38.36	$38.35	$38.40
Purchase #3	$93.37	10.857%	$103.5072	$103.51	$103.50	$103.50
Purchase #4	$22.30	3.453%	$23.07	$23.07	$23.05	$23.10
Purchase #5	$54.61	12.556%	$61.4668	$61.47	$61.45	$61.50
Purchase #6	$17.72	6.850%	$18.9338	$18.93	$18.95	$18.90
Purchase #7	$77.45	5.132%	$81.4247	$81.42	$81.40	$81.40
7 purchase totals =	$419.46		$459.6714	$459.67	$459.60	$459.70