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	$220.86	7.291%	$236.9629	$236.96	$236.95	$237.00
Purchase #2	$94.35	6.635%	$100.6101	$100.61	$100.60	$100.60
Purchase #3	$106.69	4.641%	$111.6415	$111.64	$111.65	$111.60
Purchase #4	$198.41	6.250%	$210.8106	$210.81	$210.80	$210.80
Purchase #5	$116.82	9.792%	$128.259	$128.26	$128.25	$128.30
Purchase #6	$43.96	13.778%	$50.0168	$50.02	$50.00	$50.00
Purchase #7	$209.30	7.769%	$225.5605	$225.56	$225.55	$225.60
7 purchase totals =	$990.39		$1,063.8614	$1,063.86	$1,063.80	$1,063.90