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	$60.53	3.302%	$62.5287	$62.53	$62.55	$62.50
Purchase #2	$236.48	8.117%	$255.6751	$255.68	$255.70	$255.70
Purchase #3	$52.84	11.702%	$59.0233	$59.02	$59.00	$59.00
Purchase #4	$162.53	11.792%	$181.6955	$181.70	$181.70	$181.70
Purchase #5	$90.50	10.537%	$100.036	$100.04	$100.05	$100.00
Purchase #6	$185.61	4.337%	$193.6599	$193.66	$193.65	$193.70
Purchase #7	$49.40	9.791%	$54.2368	$54.24	$54.25	$54.20
7 purchase totals =	$837.89		$906.8553	$906.87	$906.90	$906.80