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	$208.85	5.793%	$220.9487	$220.95	$220.95	$220.90
Purchase #2	$26.89	3.748%	$27.8978	$27.90	$27.90	$27.90
Purchase #3	$139.32	12.346%	$156.5204	$156.52	$156.50	$156.50
Purchase #4	$59.47	5.503%	$62.7426	$62.74	$62.75	$62.70
Purchase #5	$224.68	13.182%	$254.2973	$254.30	$254.30	$254.30
Purchase #6	$76.62	13.594%	$87.0357	$87.04	$87.05	$87.00
Purchase #7	$172.85	13.535%	$196.2452	$196.25	$196.25	$196.20
7 purchase totals =	$908.68		$1,005.6877	$1,005.70	$1,005.70	$1,005.50