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	$123.26	7.761%	$132.8262	$132.83	$132.85	$132.80
Purchase #2	$196.89	8.137%	$212.9109	$212.91	$212.90	$212.90
Purchase #3	$76.93	8.298%	$83.3137	$83.31	$83.30	$83.30
Purchase #4	$193.80	11.192%	$215.4901	$215.49	$215.50	$215.50
Purchase #5	$92.70	8.185%	$100.2875	$100.29	$100.30	$100.30
Purchase #6	$192.86	13.291%	$218.493	$218.49	$218.50	$218.50
Purchase #7	$135.59	6.157%	$143.9383	$143.94	$143.95	$143.90
7 purchase totals =	$1,012.03		$1,107.2597	$1,107.26	$1,107.30	$1,107.20