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	$212.64	10.120%	$234.1592	$234.16	$234.15	$234.20
Purchase #2	$80.67	10.442%	$89.0936	$89.09	$89.10	$89.10
Purchase #3	$13.78	10.665%	$15.2496	$15.25	$15.25	$15.20
Purchase #4	$131.83	11.839%	$147.4374	$147.44	$147.45	$147.40
Purchase #5	$51.87	5.652%	$54.8017	$54.80	$54.80	$54.80
Purchase #6	$218.90	11.479%	$244.0275	$244.03	$244.05	$244.00
Purchase #7	$117.83	8.343%	$127.6606	$127.66	$127.65	$127.70
7 purchase totals =	$827.52		$912.4296	$912.43	$912.45	$912.40