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	$217.76	7.769%	$234.6778	$234.68	$234.70	$234.70
Purchase #2	$190.64	4.162%	$198.5744	$198.57	$198.55	$198.60
Purchase #3	$155.30	8.678%	$168.7769	$168.78	$168.80	$168.80
Purchase #4	$78.72	12.332%	$88.4278	$88.43	$88.45	$88.40
Purchase #5	$116.28	13.590%	$132.0825	$132.08	$132.10	$132.10
Purchase #6	$134.98	7.823%	$145.5395	$145.54	$145.55	$145.50
Purchase #7	$167.66	10.409%	$185.1117	$185.11	$185.10	$185.10
7 purchase totals =	$1,061.34		$1,153.1906	$1,153.19	$1,153.25	$1,153.20