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	$240.34	9.234%	$262.533	$262.53	$262.55	$262.50
Purchase #2	$62.36	3.737%	$64.6904	$64.69	$64.70	$64.70
Purchase #3	$200.43	12.484%	$225.4517	$225.45	$225.45	$225.50
Purchase #4	$239.65	7.107%	$256.6819	$256.68	$256.70	$256.70
Purchase #5	$109.48	7.874%	$118.1005	$118.10	$118.10	$118.10
Purchase #6	$127.32	12.396%	$143.1026	$143.10	$143.10	$143.10
Purchase #7	$191.78	4.509%	$200.4274	$200.43	$200.45	$200.40
7 purchase totals =	$1,171.36		$1,270.9875	$1,270.98	$1,271.05	$1,271.00