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	$160.41	4.424%	$167.5065	$167.51	$167.50	$167.50
Purchase #2	$73.66	3.287%	$76.0812	$76.08	$76.10	$76.10
Purchase #3	$226.32	8.719%	$246.0528	$246.05	$246.05	$246.10
Purchase #4	$234.35	10.382%	$258.6802	$258.68	$258.70	$258.70
Purchase #5	$88.60	12.618%	$99.7795	$99.78	$99.80	$99.80
Purchase #6	$100.66	12.720%	$113.464	$113.46	$113.45	$113.50
Purchase #7	$94.53	5.306%	$99.5458	$99.55	$99.55	$99.50
7 purchase totals =	$978.53		$1,061.1100	$1,061.11	$1,061.15	$1,061.20