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	$82.39	6.320%	$87.597	$87.60	$87.60	$87.60
Purchase #2	$58.53	13.183%	$66.246	$66.25	$66.25	$66.20
Purchase #3	$108.31	3.241%	$111.8203	$111.82	$111.80	$111.80
Purchase #4	$243.41	9.666%	$266.938	$266.94	$266.95	$266.90
Purchase #5	$201.38	10.619%	$222.7645	$222.76	$222.75	$222.80
Purchase #6	$215.34	12.153%	$241.5103	$241.51	$241.50	$241.50
Purchase #7	$95.67	13.413%	$108.5022	$108.50	$108.50	$108.50
7 purchase totals =	$1,005.03		$1,105.3783	$1,105.38	$1,105.35	$1,105.30