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	$59.60	4.144%	$62.0698	$62.07	$62.05	$62.10
Purchase #2	$102.90	8.711%	$111.8636	$111.86	$111.85	$111.90
Purchase #3	$48.64	3.538%	$50.3609	$50.36	$50.35	$50.40
Purchase #4	$185.29	11.854%	$207.2543	$207.25	$207.25	$207.30
Purchase #5	$234.67	10.675%	$259.721	$259.72	$259.70	$259.70
Purchase #6	$32.65	3.583%	$33.8198	$33.82	$33.80	$33.80
Purchase #7	$119.33	12.622%	$134.3918	$134.39	$134.40	$134.40
7 purchase totals =	$783.08		$859.4812	$859.47	$859.40	$859.60