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	$10.69	3.449%	$11.0587	$11.06	$11.05	$11.10
Purchase #2	$157.89	12.108%	$177.0073	$177.01	$177.00	$177.00
Purchase #3	$13.85	10.360%	$15.2849	$15.28	$15.30	$15.30
Purchase #4	$79.35	13.854%	$90.3431	$90.34	$90.35	$90.30
Purchase #5	$35.44	7.507%	$38.1005	$38.10	$38.10	$38.10
Purchase #6	$100.46	5.132%	$105.6156	$105.62	$105.60	$105.60
Purchase #7	$247.51	11.757%	$276.6098	$276.61	$276.60	$276.60
7 purchase totals =	$645.19		$714.0199	$714.02	$714.00	$714.00