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	$195.27	9.724%	$214.2581	$214.26	$214.25	$214.30
Purchase #2	$45.72	12.293%	$51.3404	$51.34	$51.35	$51.30
Purchase #3	$247.38	3.676%	$256.4737	$256.47	$256.45	$256.50
Purchase #4	$199.60	9.490%	$218.542	$218.54	$218.55	$218.50
Purchase #5	$11.84	4.526%	$12.3759	$12.38	$12.40	$12.40
Purchase #6	$246.98	6.802%	$263.7796	$263.78	$263.80	$263.80
Purchase #7	$33.33	13.244%	$37.7442	$37.74	$37.75	$37.70
7 purchase totals =	$980.12		$1,054.5139	$1,054.51	$1,054.55	$1,054.50