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	$151.43	10.497%	$167.3256	$167.33	$167.35	$167.30
Purchase #2	$86.37	11.151%	$96.0011	$96.00	$96.00	$96.00
Purchase #3	$88.96	12.684%	$100.2437	$100.24	$100.25	$100.20
Purchase #4	$80.33	11.775%	$89.7889	$89.79	$89.80	$89.80
Purchase #5	$215.31	11.382%	$239.8166	$239.82	$239.80	$239.80
Purchase #6	$10.38	13.738%	$11.806	$11.81	$11.80	$11.80
Purchase #7	$48.86	5.202%	$51.4017	$51.40	$51.40	$51.40
7 purchase totals =	$681.64		$756.3836	$756.39	$756.40	$756.30