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	$52.80	11.160%	$58.6925	$58.69	$58.70	$58.70
Purchase #2	$64.56	11.161%	$71.7655	$71.77	$71.75	$71.80
Purchase #3	$22.96	5.392%	$24.198	$24.20	$24.20	$24.20
Purchase #4	$61.35	6.387%	$65.2684	$65.27	$65.25	$65.30
Purchase #5	$186.72	12.249%	$209.5913	$209.59	$209.60	$209.60
Purchase #6	$88.61	13.742%	$100.7868	$100.79	$100.80	$100.80
Purchase #7	$76.40	11.571%	$85.2402	$85.24	$85.25	$85.20
7 purchase totals =	$553.40		$615.5427	$615.55	$615.55	$615.60