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	$58.85	6.280%	$62.5458	$62.55	$62.55	$62.50
Purchase #2	$213.62	10.237%	$235.4883	$235.49	$235.50	$235.50
Purchase #3	$55.61	6.596%	$59.278	$59.28	$59.30	$59.30
Purchase #4	$46.77	5.659%	$49.4167	$49.42	$49.40	$49.40
Purchase #5	$235.76	11.507%	$262.8889	$262.89	$262.90	$262.90
Purchase #6	$158.78	11.503%	$177.0445	$177.04	$177.05	$177.00
Purchase #7	$96.42	4.385%	$100.648	$100.65	$100.65	$100.60
7 purchase totals =	$865.81		$947.3102	$947.32	$947.35	$947.20