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	$176.63	11.265%	$196.5274	$196.53	$196.55	$196.50
Purchase #2	$114.96	10.436%	$126.9572	$126.96	$126.95	$127.00
Purchase #3	$159.43	8.242%	$172.5702	$172.57	$172.55	$172.60
Purchase #4	$114.56	10.250%	$126.3024	$126.30	$126.30	$126.30
Purchase #5	$174.77	6.313%	$185.8032	$185.80	$185.80	$185.80
Purchase #6	$51.68	7.168%	$55.3844	$55.38	$55.40	$55.40
Purchase #7	$48.61	5.617%	$51.3404	$51.34	$51.35	$51.30
7 purchase totals =	$840.64		$914.8852	$914.88	$914.90	$914.90