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	$214.45	11.419%	$238.938	$238.94	$238.95	$238.90
Purchase #2	$68.85	3.345%	$71.153	$71.15	$71.15	$71.20
Purchase #3	$197.25	5.805%	$208.7004	$208.70	$208.70	$208.70
Purchase #4	$187.57	12.347%	$210.7293	$210.73	$210.75	$210.70
Purchase #5	$137.86	10.524%	$152.3684	$152.37	$152.35	$152.40
Purchase #6	$15.91	13.176%	$18.0063	$18.01	$18.00	$18.00
Purchase #7	$160.92	4.686%	$168.4607	$168.46	$168.45	$168.50
7 purchase totals =	$982.81		$1,068.3561	$1,068.36	$1,068.35	$1,068.40