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	$46.99	12.136%	$52.6927	$52.69	$52.70	$52.70
Purchase #2	$64.39	5.347%	$67.8329	$67.83	$67.85	$67.80
Purchase #3	$33.80	9.724%	$37.0867	$37.09	$37.10	$37.10
Purchase #4	$135.89	5.144%	$142.8802	$142.88	$142.90	$142.90
Purchase #5	$227.78	6.548%	$242.695	$242.70	$242.70	$242.70
Purchase #6	$222.31	6.119%	$235.9131	$235.91	$235.90	$235.90
Purchase #7	$229.69	3.246%	$237.1457	$237.15	$237.15	$237.10
7 purchase totals =	$960.85		$1,016.2463	$1,016.25	$1,016.30	$1,016.20