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	$211.55	7.508%	$227.4332	$227.43	$227.45	$227.40
Purchase #2	$231.81	6.534%	$246.9565	$246.96	$246.95	$247.00
Purchase #3	$35.61	11.189%	$39.5944	$39.59	$39.60	$39.60
Purchase #4	$170.46	5.391%	$179.6495	$179.65	$179.65	$179.60
Purchase #5	$34.89	3.802%	$36.2165	$36.22	$36.20	$36.20
Purchase #6	$162.79	13.565%	$184.8725	$184.87	$184.85	$184.90
Purchase #7	$176.28	5.246%	$185.5276	$185.53	$185.55	$185.50
7 purchase totals =	$1,023.39		$1,100.2502	$1,100.25	$1,100.25	$1,100.20