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	$221.27	11.593%	$246.9218	$246.92	$246.90	$246.90
Purchase #2	$57.45	7.667%	$61.8547	$61.85	$61.85	$61.90
Purchase #3	$116.67	5.722%	$123.3459	$123.35	$123.35	$123.30
Purchase #4	$25.60	7.743%	$27.5822	$27.58	$27.60	$27.60
Purchase #5	$68.50	11.164%	$76.1473	$76.15	$76.15	$76.10
Purchase #6	$53.72	10.191%	$59.1946	$59.19	$59.20	$59.20
Purchase #7	$98.32	7.786%	$105.9752	$105.98	$106.00	$106.00
7 purchase totals =	$641.53		$701.0217	$701.02	$701.05	$701.00