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	$172.75	12.847%	$194.9432	$194.94	$194.95	$194.90
Purchase #2	$146.63	3.222%	$151.3544	$151.35	$151.35	$151.40
Purchase #3	$190.34	10.522%	$210.3676	$210.37	$210.35	$210.40
Purchase #4	$12.46	8.510%	$13.5203	$13.52	$13.50	$13.50
Purchase #5	$99.49	5.789%	$105.2495	$105.25	$105.25	$105.20
Purchase #6	$128.85	5.761%	$136.273	$136.27	$136.25	$136.30
Purchase #7	$216.40	7.145%	$231.8618	$231.86	$231.85	$231.90
7 purchase totals =	$966.92		$1,043.5698	$1,043.56	$1,043.50	$1,043.60