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	$182.78	7.746%	$196.9381	$196.94	$196.95	$196.90
Purchase #2	$165.77	9.466%	$181.4618	$181.46	$181.45	$181.50
Purchase #3	$144.83	4.285%	$151.036	$151.04	$151.05	$151.00
Purchase #4	$249.43	4.447%	$260.5222	$260.52	$260.50	$260.50
Purchase #5	$231.72	8.200%	$250.721	$250.72	$250.70	$250.70
Purchase #6	$175.82	12.468%	$197.7412	$197.74	$197.75	$197.70
Purchase #7	$6.95	13.388%	$7.8805	$7.88	$7.90	$7.90
7 purchase totals =	$1,157.30		$1,246.3008	$1,246.30	$1,246.30	$1,246.20