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	$59.27	10.535%	$65.5141	$65.51	$65.50	$65.50
Purchase #2	$182.55	7.615%	$196.4512	$196.45	$196.45	$196.50
Purchase #3	$203.87	10.559%	$225.3966	$225.40	$225.40	$225.40
Purchase #4	$220.81	10.295%	$243.5424	$243.54	$243.55	$243.50
Purchase #5	$211.35	8.620%	$229.5684	$229.57	$229.55	$229.60
Purchase #6	$11.96	8.513%	$12.9782	$12.98	$13.00	$13.00
Purchase #7	$57.85	3.663%	$59.969	$59.97	$59.95	$60.00
7 purchase totals =	$947.66		$1,033.4199	$1,033.42	$1,033.40	$1,033.50