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	$113.84	8.574%	$123.6006	$123.60	$123.60	$123.60
Purchase #2	$185.97	5.592%	$196.3694	$196.37	$196.35	$196.40
Purchase #3	$170.68	6.354%	$181.525	$181.53	$181.55	$181.50
Purchase #4	$224.95	12.715%	$253.5524	$253.55	$253.55	$253.60
Purchase #5	$42.65	7.800%	$45.9767	$45.98	$46.00	$46.00
Purchase #6	$66.35	7.801%	$71.526	$71.53	$71.55	$71.50
Purchase #7	$186.98	4.421%	$195.2464	$195.25	$195.25	$195.20
7 purchase totals =	$991.42		$1,067.7965	$1,067.81	$1,067.85	$1,067.80