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	$147.72	10.249%	$162.8598	$162.86	$162.85	$162.90
Purchase #2	$138.81	4.798%	$145.4701	$145.47	$145.45	$145.50
Purchase #3	$33.62	4.377%	$35.0915	$35.09	$35.10	$35.10
Purchase #4	$52.55	6.362%	$55.8932	$55.89	$55.90	$55.90
Purchase #5	$94.56	11.833%	$105.7493	$105.75	$105.75	$105.70
Purchase #6	$125.73	8.826%	$136.8269	$136.83	$136.85	$136.80
Purchase #7	$17.82	12.622%	$20.0692	$20.07	$20.05	$20.10
7 purchase totals =	$610.81		$661.9600	$661.96	$661.95	$662.00