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	$193.98	3.390%	$200.5559	$200.56	$200.55	$200.60
Purchase #2	$212.25	13.763%	$241.462	$241.46	$241.45	$241.50
Purchase #3	$205.63	10.631%	$227.4905	$227.49	$227.50	$227.50
Purchase #4	$156.78	10.592%	$173.3861	$173.39	$173.40	$173.40
Purchase #5	$146.74	12.298%	$164.7861	$164.79	$164.80	$164.80
Purchase #6	$84.90	5.721%	$89.7571	$89.76	$89.75	$89.80
Purchase #7	$33.29	10.681%	$36.8457	$36.85	$36.85	$36.80
7 purchase totals =	$1,033.57		$1,134.2834	$1,134.30	$1,134.30	$1,134.40