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	$56.27	10.286%	$62.0579	$62.06	$62.05	$62.10
Purchase #2	$157.97	11.784%	$176.5852	$176.59	$176.60	$176.60
Purchase #3	$159.33	4.574%	$166.6178	$166.62	$166.60	$166.60
Purchase #4	$12.40	12.217%	$13.9149	$13.91	$13.90	$13.90
Purchase #5	$136.79	10.768%	$151.5195	$151.52	$151.50	$151.50
Purchase #6	$72.88	4.225%	$75.9592	$75.96	$75.95	$76.00
Purchase #7	$105.85	9.808%	$116.2318	$116.23	$116.25	$116.20
7 purchase totals =	$701.49		$762.8863	$762.89	$762.85	$762.90