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	$65.50	11.253%	$72.8707	$72.87	$72.85	$72.90
Purchase #2	$108.85	13.661%	$123.72	$123.72	$123.70	$123.70
Purchase #3	$58.70	10.632%	$64.941	$64.94	$64.95	$64.90
Purchase #4	$242.27	5.419%	$255.3986	$255.40	$255.40	$255.40
Purchase #5	$171.48	6.861%	$183.2452	$183.25	$183.25	$183.20
Purchase #6	$217.74	5.390%	$229.4762	$229.48	$229.50	$229.50
Purchase #7	$127.31	3.712%	$132.0357	$132.04	$132.05	$132.00
7 purchase totals =	$991.85		$1,061.6874	$1,061.70	$1,061.70	$1,061.60