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	$40.72	13.527%	$46.2282	$46.23	$46.25	$46.20
Purchase #2	$157.98	11.853%	$176.7054	$176.71	$176.70	$176.70
Purchase #3	$165.42	10.505%	$182.7974	$182.80	$182.80	$182.80
Purchase #4	$187.50	4.712%	$196.335	$196.34	$196.35	$196.30
Purchase #5	$224.90	3.110%	$231.8944	$231.89	$231.90	$231.90
Purchase #6	$154.79	11.443%	$172.5026	$172.50	$172.50	$172.50
Purchase #7	$32.26	7.214%	$34.5872	$34.59	$34.60	$34.60
7 purchase totals =	$963.57		$1,041.0502	$1,041.06	$1,041.10	$1,041.00