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	$168.76	10.577%	$186.6097	$186.61	$186.60	$186.60
Purchase #2	$204.82	11.221%	$227.8029	$227.80	$227.80	$227.80
Purchase #3	$233.83	7.525%	$251.4257	$251.43	$251.45	$251.40
Purchase #4	$221.65	7.565%	$238.4178	$238.42	$238.40	$238.40
Purchase #5	$12.70	4.519%	$13.2739	$13.27	$13.25	$13.30
Purchase #6	$240.96	6.481%	$256.5766	$256.58	$256.60	$256.60
Purchase #7	$180.82	5.548%	$190.8519	$190.85	$190.85	$190.90
7 purchase totals =	$1,263.54		$1,364.9585	$1,364.96	$1,364.95	$1,365.00