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	$211.50	5.334%	$222.7814	$222.78	$222.80	$222.80
Purchase #2	$95.70	7.643%	$103.0144	$103.01	$103.00	$103.00
Purchase #3	$13.45	12.845%	$15.1777	$15.18	$15.20	$15.20
Purchase #4	$135.55	10.697%	$150.0498	$150.05	$150.05	$150.00
Purchase #5	$167.94	6.833%	$179.4153	$179.42	$179.40	$179.40
Purchase #6	$158.34	6.636%	$168.8474	$168.85	$168.85	$168.80
Purchase #7	$173.64	11.533%	$193.6659	$193.67	$193.65	$193.70
7 purchase totals =	$956.12		$1,032.9519	$1,032.96	$1,032.95	$1,032.90