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	$192.32	6.874%	$205.5401	$205.54	$205.55	$205.50
Purchase #2	$61.54	7.731%	$66.2977	$66.30	$66.30	$66.30
Purchase #3	$185.80	5.296%	$195.64	$195.64	$195.65	$195.60
Purchase #4	$162.78	3.549%	$168.5571	$168.56	$168.55	$168.60
Purchase #5	$108.28	4.188%	$112.8148	$112.81	$112.80	$112.80
Purchase #6	$237.93	3.780%	$246.9238	$246.92	$246.90	$246.90
Purchase #7	$11.42	8.398%	$12.3791	$12.38	$12.40	$12.40
7 purchase totals =	$960.07		$1,008.1526	$1,008.15	$1,008.15	$1,008.10