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	$156.47	3.552%	$162.0278	$162.03	$162.05	$162.00
Purchase #2	$122.40	8.229%	$132.4723	$132.47	$132.45	$132.50
Purchase #3	$7.94	5.273%	$8.3587	$8.36	$8.35	$8.40
Purchase #4	$89.83	10.558%	$99.3143	$99.31	$99.30	$99.30
Purchase #5	$57.61	12.828%	$65.0002	$65.00	$65.00	$65.00
Purchase #6	$104.95	6.360%	$111.6248	$111.62	$111.60	$111.60
Purchase #7	$121.34	10.763%	$134.3998	$134.40	$134.40	$134.40
7 purchase totals =	$660.54		$713.1979	$713.19	$713.15	$713.20