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	$217.53	13.483%	$246.8596	$246.86	$246.85	$246.90
Purchase #2	$69.58	4.791%	$72.9136	$72.91	$72.90	$72.90
Purchase #3	$81.27	13.715%	$92.4162	$92.42	$92.40	$92.40
Purchase #4	$91.89	13.594%	$104.3815	$104.38	$104.40	$104.40
Purchase #5	$173.46	13.151%	$196.2717	$196.27	$196.25	$196.30
Purchase #6	$142.27	9.655%	$156.0062	$156.01	$156.00	$156.00
Purchase #7	$147.50	11.144%	$163.9374	$163.94	$163.95	$163.90
7 purchase totals =	$923.50		$1,032.7862	$1,032.79	$1,032.75	$1,032.80