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	$241.28	9.471%	$264.1316	$264.13	$264.15	$264.10
Purchase #2	$116.52	13.739%	$132.5287	$132.53	$132.55	$132.50
Purchase #3	$88.58	7.220%	$94.9755	$94.98	$95.00	$95.00
Purchase #4	$185.39	6.197%	$196.8786	$196.88	$196.90	$196.90
Purchase #5	$86.25	7.229%	$92.485	$92.49	$92.50	$92.50
Purchase #6	$9.97	7.733%	$10.741	$10.74	$10.75	$10.70
Purchase #7	$154.31	10.704%	$170.8273	$170.83	$170.85	$170.80
7 purchase totals =	$882.30		$962.5677	$962.58	$962.70	$962.50