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	$70.69	7.715%	$76.1437	$76.14	$76.15	$76.10
Purchase #2	$47.52	3.118%	$49.0017	$49.00	$49.00	$49.00
Purchase #3	$36.32	6.392%	$38.6416	$38.64	$38.65	$38.60
Purchase #4	$59.71	5.200%	$62.8149	$62.81	$62.80	$62.80
Purchase #5	$55.68	12.446%	$62.6099	$62.61	$62.60	$62.60
Purchase #6	$84.32	6.253%	$89.5925	$89.59	$89.60	$89.60
Purchase #7	$83.80	5.511%	$88.4182	$88.42	$88.40	$88.40
7 purchase totals =	$438.04		$467.2225	$467.21	$467.20	$467.10