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	$64.82	10.839%	$71.8458	$71.85	$71.85	$71.80
Purchase #2	$180.56	11.299%	$200.9615	$200.96	$200.95	$201.00
Purchase #3	$87.26	12.779%	$98.411	$98.41	$98.40	$98.40
Purchase #4	$179.60	11.575%	$200.3887	$200.39	$200.40	$200.40
Purchase #5	$208.62	11.715%	$233.0598	$233.06	$233.05	$233.10
Purchase #6	$199.83	12.346%	$224.501	$224.50	$224.50	$224.50
Purchase #7	$31.69	11.725%	$35.4057	$35.41	$35.40	$35.40
7 purchase totals =	$952.38		$1,064.5735	$1,064.58	$1,064.55	$1,064.60