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	$110.68	4.816%	$116.0103	$116.01	$116.00	$116.00
Purchase #2	$15.52	9.858%	$17.05	$17.05	$17.05	$17.10
Purchase #3	$235.93	9.456%	$258.2395	$258.24	$258.25	$258.20
Purchase #4	$229.43	9.144%	$250.4091	$250.41	$250.40	$250.40
Purchase #5	$90.75	10.690%	$100.4512	$100.45	$100.45	$100.50
Purchase #6	$140.72	7.791%	$151.6835	$151.68	$151.70	$151.70
Purchase #7	$132.68	13.463%	$150.5427	$150.54	$150.55	$150.50
7 purchase totals =	$955.71		$1,044.3863	$1,044.38	$1,044.40	$1,044.40