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	$233.33	12.616%	$262.7669	$262.77	$262.75	$262.80
Purchase #2	$126.33	11.343%	$140.6596	$140.66	$140.65	$140.70
Purchase #3	$176.43	7.537%	$189.7275	$189.73	$189.75	$189.70
Purchase #4	$88.58	10.219%	$97.632	$97.63	$97.65	$97.60
Purchase #5	$182.43	4.585%	$190.7944	$190.79	$190.80	$190.80
Purchase #6	$97.67	8.334%	$105.8098	$105.81	$105.80	$105.80
Purchase #7	$189.67	10.103%	$208.8324	$208.83	$208.85	$208.80
7 purchase totals =	$1,094.44		$1,196.2226	$1,196.22	$1,196.25	$1,196.20