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	$46.69	4.861%	$48.9596	$48.96	$48.95	$49.00
Purchase #2	$142.90	5.628%	$150.9424	$150.94	$150.95	$150.90
Purchase #3	$195.84	5.130%	$205.8866	$205.89	$205.90	$205.90
Purchase #4	$153.43	3.146%	$158.2569	$158.26	$158.25	$158.30
Purchase #5	$153.39	7.471%	$164.8498	$164.85	$164.85	$164.80
Purchase #6	$166.84	5.408%	$175.8627	$175.86	$175.85	$175.90
Purchase #7	$133.69	7.746%	$144.0456	$144.05	$144.05	$144.00
7 purchase totals =	$992.78		$1,048.8036	$1,048.81	$1,048.80	$1,048.80