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	$114.94	10.416%	$126.9122	$126.91	$126.90	$126.90
Purchase #2	$50.87	13.162%	$57.5655	$57.57	$57.55	$57.60
Purchase #3	$28.56	12.361%	$32.0903	$32.09	$32.10	$32.10
Purchase #4	$121.82	3.405%	$125.968	$125.97	$125.95	$126.00
Purchase #5	$144.77	13.854%	$164.8264	$164.83	$164.85	$164.80
Purchase #6	$127.89	6.563%	$136.2834	$136.28	$136.30	$136.30
Purchase #7	$138.43	10.355%	$152.7644	$152.76	$152.75	$152.80
7 purchase totals =	$727.28		$796.4102	$796.41	$796.40	$796.50