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	$219.77	11.300%	$244.604	$244.60	$244.60	$244.60
Purchase #2	$82.94	3.334%	$85.7052	$85.71	$85.70	$85.70
Purchase #3	$231.54	3.500%	$239.6439	$239.64	$239.65	$239.60
Purchase #4	$54.96	8.433%	$59.5948	$59.59	$59.60	$59.60
Purchase #5	$156.78	4.337%	$163.5795	$163.58	$163.60	$163.60
Purchase #6	$88.77	4.586%	$92.841	$92.84	$92.85	$92.80
Purchase #7	$114.99	7.294%	$123.3774	$123.38	$123.40	$123.40
7 purchase totals =	$949.75		$1,009.3458	$1,009.34	$1,009.40	$1,009.30