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	$198.64	8.572%	$215.6674	$215.67	$215.65	$215.70
Purchase #2	$13.67	8.660%	$14.8538	$14.85	$14.85	$14.90
Purchase #3	$67.31	8.224%	$72.8456	$72.85	$72.85	$72.80
Purchase #4	$131.90	4.473%	$137.7999	$137.80	$137.80	$137.80
Purchase #5	$38.98	11.870%	$43.6069	$43.61	$43.60	$43.60
Purchase #6	$151.29	4.161%	$157.5852	$157.59	$157.60	$157.60
Purchase #7	$128.55	13.230%	$145.5572	$145.56	$145.55	$145.60
7 purchase totals =	$730.34		$787.9160	$787.93	$787.90	$788.00