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	$242.81	9.311%	$265.418	$265.42	$265.40	$265.40
Purchase #2	$240.63	10.247%	$265.2874	$265.29	$265.30	$265.30
Purchase #3	$116.32	9.400%	$127.2541	$127.25	$127.25	$127.30
Purchase #4	$182.50	4.587%	$190.8713	$190.87	$190.85	$190.90
Purchase #5	$47.54	13.616%	$54.013	$54.01	$54.00	$54.00
Purchase #6	$126.27	9.826%	$138.6773	$138.68	$138.70	$138.70
Purchase #7	$100.57	12.276%	$112.916	$112.92	$112.90	$112.90
7 purchase totals =	$1,056.64		$1,154.4371	$1,154.44	$1,154.40	$1,154.50