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	$208.46	10.745%	$230.859	$230.86	$230.85	$230.90
Purchase #2	$29.99	13.720%	$34.1046	$34.10	$34.10	$34.10
Purchase #3	$248.51	13.412%	$281.8402	$281.84	$281.85	$281.80
Purchase #4	$116.34	13.127%	$131.612	$131.61	$131.60	$131.60
Purchase #5	$105.84	9.466%	$115.8588	$115.86	$115.85	$115.90
Purchase #6	$169.74	6.379%	$180.5677	$180.57	$180.55	$180.60
Purchase #7	$83.41	3.228%	$86.1025	$86.10	$86.10	$86.10
7 purchase totals =	$962.29		$1,060.9448	$1,060.94	$1,060.90	$1,061.00