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	$125.85	3.423%	$130.1578	$130.16	$130.15	$130.20
Purchase #2	$18.58	10.524%	$20.5354	$20.54	$20.55	$20.50
Purchase #3	$47.85	9.239%	$52.2709	$52.27	$52.25	$52.30
Purchase #4	$122.59	11.702%	$136.9355	$136.94	$136.95	$136.90
Purchase #5	$102.82	8.323%	$111.3777	$111.38	$111.40	$111.40
Purchase #6	$234.86	12.243%	$263.6139	$263.61	$263.60	$263.60
Purchase #7	$203.58	7.148%	$218.1319	$218.13	$218.15	$218.10
7 purchase totals =	$856.13		$933.0231	$933.03	$933.05	$933.00