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	$63.89	13.661%	$72.618	$72.62	$72.60	$72.60
Purchase #2	$196.52	11.626%	$219.3674	$219.37	$219.35	$219.40
Purchase #3	$126.98	11.323%	$141.3579	$141.36	$141.35	$141.40
Purchase #4	$242.94	7.383%	$260.8763	$260.88	$260.90	$260.90
Purchase #5	$147.87	5.647%	$156.2202	$156.22	$156.20	$156.20
Purchase #6	$19.84	13.258%	$22.4704	$22.47	$22.45	$22.50
Purchase #7	$127.93	11.609%	$142.7814	$142.78	$142.80	$142.80
7 purchase totals =	$925.97		$1,015.6916	$1,015.70	$1,015.65	$1,015.80