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	$182.44	4.425%	$190.513	$190.51	$190.50	$190.50
Purchase #2	$209.53	10.265%	$231.0383	$231.04	$231.05	$231.00
Purchase #3	$49.51	9.176%	$54.053	$54.05	$54.05	$54.10
Purchase #4	$247.45	5.787%	$261.7699	$261.77	$261.75	$261.80
Purchase #5	$89.37	12.339%	$100.3974	$100.40	$100.40	$100.40
Purchase #6	$92.36	9.247%	$100.9005	$100.90	$100.90	$100.90
Purchase #7	$158.72	5.418%	$167.3194	$167.32	$167.30	$167.30
7 purchase totals =	$1,029.38		$1,105.9915	$1,105.99	$1,105.95	$1,106.00