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	$105.94	5.787%	$112.0707	$112.07	$112.05	$112.10
Purchase #2	$246.40	13.844%	$280.5116	$280.51	$280.50	$280.50
Purchase #3	$230.33	4.583%	$240.886	$240.89	$240.90	$240.90
Purchase #4	$174.82	6.186%	$185.6344	$185.63	$185.65	$185.60
Purchase #5	$179.62	13.515%	$203.8956	$203.90	$203.90	$203.90
Purchase #6	$30.64	13.679%	$34.8312	$34.83	$34.85	$34.80
Purchase #7	$107.54	4.178%	$112.033	$112.03	$112.05	$112.00
7 purchase totals =	$1,075.29		$1,169.8625	$1,169.86	$1,169.90	$1,169.80