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	$188.63	7.873%	$203.4808	$203.48	$203.50	$203.50
Purchase #2	$85.43	7.553%	$91.8825	$91.88	$91.90	$91.90
Purchase #3	$169.94	11.523%	$189.5222	$189.52	$189.50	$189.50
Purchase #4	$48.73	10.612%	$53.9012	$53.90	$53.90	$53.90
Purchase #5	$152.72	3.557%	$158.1523	$158.15	$158.15	$158.20
Purchase #6	$5.89	13.429%	$6.681	$6.68	$6.70	$6.70
Purchase #7	$76.32	8.221%	$82.5943	$82.59	$82.60	$82.60
7 purchase totals =	$727.66		$786.2143	$786.20	$786.25	$786.30