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	$201.51	8.608%	$218.856	$218.86	$218.85	$218.90
Purchase #2	$94.65	4.340%	$98.7578	$98.76	$98.75	$98.80
Purchase #3	$185.58	5.661%	$196.0857	$196.09	$196.10	$196.10
Purchase #4	$185.27	11.193%	$206.0073	$206.01	$206.00	$206.00
Purchase #5	$24.43	4.396%	$25.5039	$25.50	$25.50	$25.50
Purchase #6	$158.49	6.388%	$168.6143	$168.61	$168.60	$168.60
Purchase #7	$84.40	7.585%	$90.8017	$90.80	$90.80	$90.80
7 purchase totals =	$934.33		$1,004.6267	$1,004.63	$1,004.60	$1,004.70