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	$200.42	13.561%	$227.599	$227.60	$227.60	$227.60
Purchase #2	$210.93	5.292%	$222.0924	$222.09	$222.10	$222.10
Purchase #3	$168.93	8.151%	$182.6995	$182.70	$182.70	$182.70
Purchase #4	$52.44	9.314%	$57.3243	$57.32	$57.30	$57.30
Purchase #5	$175.87	13.734%	$200.024	$200.02	$200.00	$200.00
Purchase #6	$72.90	4.682%	$76.3132	$76.31	$76.30	$76.30
Purchase #7	$6.45	12.376%	$7.2483	$7.25	$7.25	$7.20
7 purchase totals =	$887.94		$973.3007	$973.29	$973.25	$973.20