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	$196.95	13.459%	$223.4575	$223.46	$223.45	$223.50
Purchase #2	$49.53	5.185%	$52.0981	$52.10	$52.10	$52.10
Purchase #3	$212.96	11.791%	$238.0701	$238.07	$238.05	$238.10
Purchase #4	$231.66	12.378%	$260.3349	$260.33	$260.35	$260.30
Purchase #5	$42.94	12.757%	$48.4179	$48.42	$48.40	$48.40
Purchase #6	$42.25	6.120%	$44.8357	$44.84	$44.85	$44.80
Purchase #7	$188.67	6.177%	$200.3241	$200.32	$200.30	$200.30
7 purchase totals =	$964.96		$1,067.5383	$1,067.54	$1,067.50	$1,067.50