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	$153.87	8.828%	$167.4536	$167.45	$167.45	$167.50
Purchase #2	$208.56	4.474%	$217.891	$217.89	$217.90	$217.90
Purchase #3	$107.29	4.180%	$111.7747	$111.77	$111.75	$111.80
Purchase #4	$24.94	4.170%	$25.98	$25.98	$26.00	$26.00
Purchase #5	$185.93	5.661%	$196.4555	$196.46	$196.45	$196.50
Purchase #6	$229.40	13.165%	$259.6005	$259.60	$259.60	$259.60
Purchase #7	$114.48	11.822%	$128.0138	$128.01	$128.00	$128.00
7 purchase totals =	$1,024.47		$1,107.1691	$1,107.16	$1,107.15	$1,107.30