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	$212.49	3.763%	$220.486	$220.49	$220.50	$220.50
Purchase #2	$64.62	8.825%	$70.3227	$70.32	$70.30	$70.30
Purchase #3	$222.97	8.300%	$241.4765	$241.48	$241.50	$241.50
Purchase #4	$75.72	8.620%	$82.2471	$82.25	$82.25	$82.20
Purchase #5	$79.49	4.282%	$82.8938	$82.89	$82.90	$82.90
Purchase #6	$155.55	5.362%	$163.8906	$163.89	$163.90	$163.90
Purchase #7	$169.50	12.551%	$190.7739	$190.77	$190.75	$190.80
7 purchase totals =	$980.34		$1,052.0906	$1,052.09	$1,052.10	$1,052.10