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	$164.69	6.762%	$175.8263	$175.83	$175.85	$175.80
Purchase #2	$228.39	9.216%	$249.4384	$249.44	$249.45	$249.40
Purchase #3	$231.58	8.312%	$250.8289	$250.83	$250.85	$250.80
Purchase #4	$198.43	9.546%	$217.3721	$217.37	$217.35	$217.40
Purchase #5	$218.33	4.107%	$227.2968	$227.30	$227.30	$227.30
Purchase #6	$150.27	4.836%	$157.5371	$157.54	$157.55	$157.50
Purchase #7	$111.45	10.730%	$123.4086	$123.41	$123.40	$123.40
7 purchase totals =	$1,303.14		$1,401.7082	$1,401.72	$1,401.75	$1,401.60