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	$107.54	8.281%	$116.4454	$116.45	$116.45	$116.40
Purchase #2	$173.44	5.364%	$182.7433	$182.74	$182.75	$182.70
Purchase #3	$144.39	12.814%	$162.8921	$162.89	$162.90	$162.90
Purchase #4	$87.45	6.698%	$93.3074	$93.31	$93.30	$93.30
Purchase #5	$102.48	8.724%	$111.4204	$111.42	$111.40	$111.40
Purchase #6	$196.66	6.602%	$209.6435	$209.64	$209.65	$209.60
Purchase #7	$171.64	12.219%	$192.6127	$192.61	$192.60	$192.60
7 purchase totals =	$983.60		$1,069.0648	$1,069.06	$1,069.05	$1,068.90