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	$104.25	6.537%	$111.0648	$111.06	$111.05	$111.10
Purchase #2	$170.63	7.519%	$183.4597	$183.46	$183.45	$183.50
Purchase #3	$213.28	4.398%	$222.6601	$222.66	$222.65	$222.70
Purchase #4	$27.52	3.440%	$28.4667	$28.47	$28.45	$28.50
Purchase #5	$22.80	3.561%	$23.6119	$23.61	$23.60	$23.60
Purchase #6	$181.82	10.355%	$200.6475	$200.65	$200.65	$200.60
Purchase #7	$164.90	9.439%	$180.4649	$180.46	$180.45	$180.50
7 purchase totals =	$885.20		$950.3756	$950.37	$950.30	$950.50