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	$97.33	10.582%	$107.6295	$107.63	$107.65	$107.60
Purchase #2	$105.62	5.545%	$111.4766	$111.48	$111.50	$111.50
Purchase #3	$189.47	13.649%	$215.3308	$215.33	$215.35	$215.30
Purchase #4	$177.25	11.440%	$197.5274	$197.53	$197.55	$197.50
Purchase #5	$115.83	9.725%	$127.0945	$127.09	$127.10	$127.10
Purchase #6	$92.43	6.845%	$98.7568	$98.76	$98.75	$98.80
Purchase #7	$164.45	8.548%	$178.5072	$178.51	$178.50	$178.50
7 purchase totals =	$942.38		$1,036.3228	$1,036.33	$1,036.40	$1,036.30