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	$197.96	8.739%	$215.2597	$215.26	$215.25	$215.30
Purchase #2	$66.36	9.106%	$72.4027	$72.40	$72.40	$72.40
Purchase #3	$172.87	7.577%	$185.9684	$185.97	$185.95	$186.00
Purchase #4	$126.93	10.276%	$139.9733	$139.97	$139.95	$140.00
Purchase #5	$131.42	8.727%	$142.889	$142.89	$142.90	$142.90
Purchase #6	$138.43	9.366%	$151.3954	$151.40	$151.40	$151.40
Purchase #7	$101.76	11.576%	$113.5397	$113.54	$113.55	$113.50
7 purchase totals =	$935.73		$1,021.4282	$1,021.43	$1,021.40	$1,021.50