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	$191.71	4.770%	$200.8546	$200.85	$200.85	$200.90
Purchase #2	$139.51	4.516%	$145.8103	$145.81	$145.80	$145.80
Purchase #3	$232.80	3.533%	$241.0248	$241.02	$241.00	$241.00
Purchase #4	$164.64	5.443%	$173.6014	$173.60	$173.60	$173.60
Purchase #5	$124.67	12.697%	$140.4993	$140.50	$140.50	$140.50
Purchase #6	$165.98	6.382%	$176.5728	$176.57	$176.55	$176.60
Purchase #7	$5.59	13.127%	$6.3238	$6.32	$6.30	$6.30
7 purchase totals =	$1,024.90		$1,084.6870	$1,084.67	$1,084.60	$1,084.70