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	$197.73	5.639%	$208.88	$208.88	$208.90	$208.90
Purchase #2	$226.52	8.423%	$245.5998	$245.60	$245.60	$245.60
Purchase #3	$53.96	9.521%	$59.0975	$59.10	$59.10	$59.10
Purchase #4	$39.90	3.359%	$41.2402	$41.24	$41.25	$41.20
Purchase #5	$197.50	6.798%	$210.9261	$210.93	$210.95	$210.90
Purchase #6	$237.54	10.659%	$262.8594	$262.86	$262.85	$262.90
Purchase #7	$179.78	4.489%	$187.8503	$187.85	$187.85	$187.90
7 purchase totals =	$1,132.93		$1,216.4533	$1,216.46	$1,216.50	$1,216.50