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	$242.67	6.747%	$259.0429	$259.04	$259.05	$259.00
Purchase #2	$246.76	7.576%	$265.4545	$265.45	$265.45	$265.50
Purchase #3	$96.46	8.537%	$104.6948	$104.69	$104.70	$104.70
Purchase #4	$241.75	10.277%	$266.5946	$266.59	$266.60	$266.60
Purchase #5	$186.88	7.252%	$200.4325	$200.43	$200.45	$200.40
Purchase #6	$175.27	9.131%	$191.2739	$191.27	$191.25	$191.30
Purchase #7	$173.89	3.492%	$179.9622	$179.96	$179.95	$180.00
7 purchase totals =	$1,363.68		$1,467.4554	$1,467.43	$1,467.45	$1,467.50