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	$67.36	4.843%	$70.6222	$70.62	$70.60	$70.60
Purchase #2	$184.29	13.465%	$209.1046	$209.10	$209.10	$209.10
Purchase #3	$92.82	8.615%	$100.8164	$100.82	$100.80	$100.80
Purchase #4	$102.49	5.648%	$108.2786	$108.28	$108.30	$108.30
Purchase #5	$193.82	11.380%	$215.8767	$215.88	$215.90	$215.90
Purchase #6	$173.38	12.359%	$194.808	$194.81	$194.80	$194.80
Purchase #7	$153.58	5.324%	$161.7566	$161.76	$161.75	$161.80
7 purchase totals =	$967.74		$1,061.2631	$1,061.27	$1,061.25	$1,061.30