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	$215.40	11.519%	$240.2119	$240.21	$240.20	$240.20
Purchase #2	$110.66	11.478%	$123.3616	$123.36	$123.35	$123.40
Purchase #3	$146.28	7.674%	$157.5055	$157.51	$157.50	$157.50
Purchase #4	$56.35	4.708%	$59.003	$59.00	$59.00	$59.00
Purchase #5	$6.70	9.321%	$7.3245	$7.32	$7.30	$7.30
Purchase #6	$182.94	7.657%	$196.9477	$196.95	$196.95	$196.90
Purchase #7	$230.42	4.589%	$240.994	$240.99	$241.00	$241.00
7 purchase totals =	$948.75		$1,025.3482	$1,025.34	$1,025.30	$1,025.30