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	$129.54	10.281%	$142.858	$142.86	$142.85	$142.90
Purchase #2	$90.75	9.636%	$99.4947	$99.49	$99.50	$99.50
Purchase #3	$239.44	6.778%	$255.6692	$255.67	$255.65	$255.70
Purchase #4	$244.55	5.803%	$258.7412	$258.74	$258.75	$258.70
Purchase #5	$101.71	10.389%	$112.2767	$112.28	$112.30	$112.30
Purchase #6	$76.90	11.501%	$85.7443	$85.74	$85.75	$85.70
Purchase #7	$109.98	10.195%	$121.1925	$121.19	$121.20	$121.20
7 purchase totals =	$992.87		$1,075.9766	$1,075.97	$1,076.00	$1,076.00