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	$86.35	3.593%	$89.4526	$89.45	$89.45	$89.50
Purchase #2	$221.87	3.631%	$229.9261	$229.93	$229.95	$229.90
Purchase #3	$140.32	4.226%	$146.2499	$146.25	$146.25	$146.20
Purchase #4	$215.82	12.388%	$242.5558	$242.56	$242.55	$242.60
Purchase #5	$87.96	3.320%	$90.8803	$90.88	$90.90	$90.90
Purchase #6	$100.53	8.714%	$109.2902	$109.29	$109.30	$109.30
Purchase #7	$109.84	6.297%	$116.7566	$116.76	$116.75	$116.80
7 purchase totals =	$962.69		$1,025.1115	$1,025.12	$1,025.15	$1,025.20