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	$208.50	6.731%	$222.5341	$222.53	$222.55	$222.50
Purchase #2	$184.29	3.207%	$190.2002	$190.20	$190.20	$190.20
Purchase #3	$13.69	5.654%	$14.464	$14.46	$14.45	$14.50
Purchase #4	$86.65	4.560%	$90.6012	$90.60	$90.60	$90.60
Purchase #5	$193.40	6.468%	$205.9091	$205.91	$205.90	$205.90
Purchase #6	$81.30	4.299%	$84.7951	$84.80	$84.80	$84.80
Purchase #7	$239.74	8.602%	$260.3624	$260.36	$260.35	$260.40
7 purchase totals =	$1,007.57		$1,068.8661	$1,068.86	$1,068.85	$1,068.90