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	$108.74	5.371%	$114.5804	$114.58	$114.60	$114.60
Purchase #2	$150.35	3.655%	$155.8453	$155.85	$155.85	$155.80
Purchase #3	$132.32	13.384%	$150.0297	$150.03	$150.05	$150.00
Purchase #4	$213.85	5.578%	$225.7786	$225.78	$225.80	$225.80
Purchase #5	$200.45	11.857%	$224.2174	$224.22	$224.20	$224.20
Purchase #6	$183.74	4.529%	$192.0616	$192.06	$192.05	$192.10
Purchase #7	$182.27	7.829%	$196.5399	$196.54	$196.55	$196.50
7 purchase totals =	$1,171.72		$1,259.0529	$1,259.06	$1,259.10	$1,259.00