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	$181.31	7.799%	$195.4504	$195.45	$195.45	$195.50
Purchase #2	$161.51	13.107%	$182.6791	$182.68	$182.70	$182.70
Purchase #3	$164.46	5.661%	$173.7701	$173.77	$173.75	$173.80
Purchase #4	$30.83	7.533%	$33.1524	$33.15	$33.15	$33.20
Purchase #5	$108.85	13.156%	$123.1703	$123.17	$123.15	$123.20
Purchase #6	$157.52	5.576%	$166.3033	$166.30	$166.30	$166.30
Purchase #7	$200.64	5.405%	$211.4846	$211.48	$211.50	$211.50
7 purchase totals =	$1,005.12		$1,086.0102	$1,086.00	$1,086.00	$1,086.20