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	$118.83	11.666%	$132.6927	$132.69	$132.70	$132.70
Purchase #2	$97.67	6.842%	$104.3526	$104.35	$104.35	$104.40
Purchase #3	$187.44	6.780%	$200.1484	$200.15	$200.15	$200.10
Purchase #4	$66.88	8.278%	$72.4163	$72.42	$72.40	$72.40
Purchase #5	$136.89	11.128%	$152.1231	$152.12	$152.10	$152.10
Purchase #6	$176.43	4.294%	$184.0059	$184.01	$184.00	$184.00
Purchase #7	$214.55	6.361%	$228.1975	$228.20	$228.20	$228.20
7 purchase totals =	$998.69		$1,073.9365	$1,073.94	$1,073.90	$1,073.90