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	$214.69	10.858%	$238.001	$238.00	$238.00	$238.00
Purchase #2	$67.61	7.357%	$72.5841	$72.58	$72.60	$72.60
Purchase #3	$59.79	12.359%	$67.1794	$67.18	$67.20	$67.20
Purchase #4	$124.69	3.301%	$128.806	$128.81	$128.80	$128.80
Purchase #5	$35.60	8.542%	$38.641	$38.64	$38.65	$38.60
Purchase #6	$135.98	9.368%	$148.7186	$148.72	$148.70	$148.70
Purchase #7	$158.46	6.839%	$169.2971	$169.30	$169.30	$169.30
7 purchase totals =	$796.82		$863.2272	$863.23	$863.25	$863.20