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	$205.54	9.205%	$224.46	$224.46	$224.45	$224.50
Purchase #2	$20.97	4.235%	$21.8581	$21.86	$21.85	$21.90
Purchase #3	$163.38	13.371%	$185.2255	$185.23	$185.25	$185.20
Purchase #4	$12.41	3.581%	$12.8544	$12.85	$12.85	$12.90
Purchase #5	$234.78	4.423%	$245.1643	$245.16	$245.15	$245.20
Purchase #6	$233.50	11.729%	$260.8872	$260.89	$260.90	$260.90
Purchase #7	$175.38	6.626%	$187.0007	$187.00	$187.00	$187.00
7 purchase totals =	$1,045.96		$1,137.4502	$1,137.45	$1,137.45	$1,137.60