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	$134.98	12.368%	$151.6743	$151.67	$151.65	$151.70
Purchase #2	$168.88	11.255%	$187.8874	$187.89	$187.90	$187.90
Purchase #3	$13.61	7.142%	$14.582	$14.58	$14.60	$14.60
Purchase #4	$196.96	5.848%	$208.4782	$208.48	$208.50	$208.50
Purchase #5	$124.81	12.698%	$140.6584	$140.66	$140.65	$140.70
Purchase #6	$190.31	5.291%	$200.3793	$200.38	$200.40	$200.40
Purchase #7	$139.35	6.832%	$148.8704	$148.87	$148.85	$148.90
7 purchase totals =	$968.90		$1,052.5300	$1,052.53	$1,052.55	$1,052.70