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	$239.98	9.547%	$262.8909	$262.89	$262.90	$262.90
Purchase #2	$57.92	8.683%	$62.9492	$62.95	$62.95	$62.90
Purchase #3	$194.31	6.746%	$207.4182	$207.42	$207.40	$207.40
Purchase #4	$196.38	12.276%	$220.4876	$220.49	$220.50	$220.50
Purchase #5	$28.86	11.545%	$32.1919	$32.19	$32.20	$32.20
Purchase #6	$208.64	6.756%	$222.7357	$222.74	$222.75	$222.70
Purchase #7	$156.56	4.857%	$164.1641	$164.16	$164.15	$164.20
7 purchase totals =	$1,082.65		$1,172.8376	$1,172.84	$1,172.85	$1,172.80