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	$216.52	11.493%	$241.4046	$241.40	$241.40	$241.40
Purchase #2	$166.86	4.478%	$174.332	$174.33	$174.35	$174.30
Purchase #3	$198.33	11.700%	$221.5346	$221.53	$221.55	$221.50
Purchase #4	$53.40	11.683%	$59.6387	$59.64	$59.65	$59.60
Purchase #5	$197.32	13.132%	$223.2321	$223.23	$223.25	$223.20
Purchase #6	$91.55	3.238%	$94.5144	$94.51	$94.50	$94.50
Purchase #7	$26.45	12.349%	$29.7163	$29.72	$29.70	$29.70
7 purchase totals =	$950.43		$1,044.3727	$1,044.36	$1,044.40	$1,044.20