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	$86.54	10.517%	$95.6414	$95.64	$95.65	$95.60
Purchase #2	$227.38	5.510%	$239.9086	$239.91	$239.90	$239.90
Purchase #3	$184.35	6.630%	$196.5724	$196.57	$196.55	$196.60
Purchase #4	$40.32	8.403%	$43.7081	$43.71	$43.70	$43.70
Purchase #5	$19.53	5.799%	$20.6625	$20.66	$20.65	$20.70
Purchase #6	$219.87	12.258%	$246.8217	$246.82	$246.80	$246.80
Purchase #7	$91.46	3.321%	$94.4974	$94.50	$94.50	$94.50
7 purchase totals =	$869.45		$937.8121	$937.81	$937.75	$937.80