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	$234.57	11.703%	$262.0217	$262.02	$262.00	$262.00
Purchase #2	$140.73	7.794%	$151.6985	$151.70	$151.70	$151.70
Purchase #3	$13.37	9.844%	$14.6861	$14.69	$14.70	$14.70
Purchase #4	$151.57	7.238%	$162.5406	$162.54	$162.55	$162.50
Purchase #5	$55.76	6.618%	$59.4502	$59.45	$59.45	$59.50
Purchase #6	$19.53	6.215%	$20.7438	$20.74	$20.75	$20.70
Purchase #7	$37.49	10.347%	$41.3691	$41.37	$41.35	$41.40
7 purchase totals =	$653.02		$712.5100	$712.51	$712.50	$712.50