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	$83.35	3.352%	$86.1439	$86.14	$86.15	$86.10
Purchase #2	$140.96	10.666%	$155.9948	$155.99	$156.00	$156.00
Purchase #3	$200.86	7.264%	$215.4505	$215.45	$215.45	$215.50
Purchase #4	$203.78	10.666%	$225.5152	$225.52	$225.50	$225.50
Purchase #5	$230.60	11.751%	$257.6978	$257.70	$257.70	$257.70
Purchase #6	$151.61	3.207%	$156.4721	$156.47	$156.45	$156.50
Purchase #7	$143.54	10.264%	$158.2729	$158.27	$158.25	$158.30
7 purchase totals =	$1,154.70		$1,255.5472	$1,255.54	$1,255.50	$1,255.60