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	$44.37	4.656%	$46.4359	$46.44	$46.45	$46.40
Purchase #2	$60.40	4.367%	$63.0377	$63.04	$63.05	$63.00
Purchase #3	$38.91	13.450%	$44.1434	$44.14	$44.15	$44.10
Purchase #4	$42.54	8.538%	$46.1721	$46.17	$46.15	$46.20
Purchase #5	$108.86	8.260%	$117.8518	$117.85	$117.85	$117.90
Purchase #6	$79.98	3.247%	$82.577	$82.58	$82.60	$82.60
Purchase #7	$59.37	4.824%	$62.234	$62.23	$62.25	$62.20
7 purchase totals =	$434.43		$462.4519	$462.45	$462.50	$462.40