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	$91.64	3.189%	$94.5624	$94.56	$94.55	$94.60
Purchase #2	$171.39	13.131%	$193.8952	$193.90	$193.90	$193.90
Purchase #3	$122.80	3.446%	$127.0317	$127.03	$127.05	$127.00
Purchase #4	$54.88	13.318%	$62.1889	$62.19	$62.20	$62.20
Purchase #5	$146.79	5.874%	$155.4124	$155.41	$155.40	$155.40
Purchase #6	$54.83	5.558%	$57.8775	$57.88	$57.90	$57.90
Purchase #7	$66.42	7.637%	$71.4925	$71.49	$71.50	$71.50
7 purchase totals =	$708.75		$762.4606	$762.46	$762.50	$762.50