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	$134.57	5.536%	$142.0198	$142.02	$142.00	$142.00
Purchase #2	$109.89	8.271%	$118.979	$118.98	$119.00	$119.00
Purchase #3	$190.26	4.534%	$198.8864	$198.89	$198.90	$198.90
Purchase #4	$166.83	11.433%	$185.9037	$185.90	$185.90	$185.90
Purchase #5	$92.37	5.650%	$97.5889	$97.59	$97.60	$97.60
Purchase #6	$156.79	13.388%	$177.781	$177.78	$177.80	$177.80
Purchase #7	$160.37	8.690%	$174.3062	$174.31	$174.30	$174.30
7 purchase totals =	$1,011.08		$1,095.4650	$1,095.47	$1,095.50	$1,095.50