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	$59.29	9.866%	$65.1396	$65.14	$65.15	$65.10
Purchase #2	$7.83	11.211%	$8.7078	$8.71	$8.70	$8.70
Purchase #3	$12.93	13.477%	$14.6726	$14.67	$14.65	$14.70
Purchase #4	$164.69	4.811%	$172.6132	$172.61	$172.60	$172.60
Purchase #5	$201.80	9.431%	$220.8318	$220.83	$220.85	$220.80
Purchase #6	$98.79	5.786%	$104.506	$104.51	$104.50	$104.50
Purchase #7	$152.37	13.436%	$172.8424	$172.84	$172.85	$172.80
7 purchase totals =	$697.70		$759.3134	$759.31	$759.30	$759.20