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	$233.61	11.767%	$261.0989	$261.10	$261.10	$261.10
Purchase #2	$38.47	13.589%	$43.6977	$43.70	$43.70	$43.70
Purchase #3	$74.81	4.352%	$78.0657	$78.07	$78.05	$78.10
Purchase #4	$230.88	10.487%	$255.0924	$255.09	$255.10	$255.10
Purchase #5	$103.66	8.874%	$112.8588	$112.86	$112.85	$112.90
Purchase #6	$201.55	10.630%	$222.9748	$222.97	$222.95	$223.00
Purchase #7	$49.50	8.501%	$53.708	$53.71	$53.70	$53.70
7 purchase totals =	$932.48		$1,027.4963	$1,027.50	$1,027.45	$1,027.60