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	$12.73	12.869%	$14.3682	$14.37	$14.35	$14.40
Purchase #2	$151.89	13.469%	$172.3481	$172.35	$172.35	$172.30
Purchase #3	$129.79	11.712%	$144.991	$144.99	$145.00	$145.00
Purchase #4	$169.82	9.730%	$186.3435	$186.34	$186.35	$186.30
Purchase #5	$215.59	7.357%	$231.451	$231.45	$231.45	$231.50
Purchase #6	$146.88	12.418%	$165.1196	$165.12	$165.10	$165.10
Purchase #7	$146.75	4.210%	$152.9282	$152.93	$152.95	$152.90
7 purchase totals =	$973.45		$1,067.5496	$1,067.55	$1,067.55	$1,067.50