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	$195.70	9.461%	$214.2152	$214.22	$214.20	$214.20
Purchase #2	$131.67	9.491%	$144.1668	$144.17	$144.15	$144.20
Purchase #3	$41.99	9.160%	$45.8363	$45.84	$45.85	$45.80
Purchase #4	$164.66	4.549%	$172.1504	$172.15	$172.15	$172.20
Purchase #5	$25.92	7.191%	$27.7839	$27.78	$27.80	$27.80
Purchase #6	$234.69	13.290%	$265.8803	$265.88	$265.90	$265.90
Purchase #7	$137.73	5.116%	$144.7763	$144.78	$144.80	$144.80
7 purchase totals =	$932.36		$1,014.8092	$1,014.82	$1,014.85	$1,014.90