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	$162.50	11.714%	$181.5353	$181.54	$181.55	$181.50
Purchase #2	$117.71	7.124%	$126.0957	$126.10	$126.10	$126.10
Purchase #3	$73.93	11.537%	$82.4593	$82.46	$82.45	$82.50
Purchase #4	$123.32	3.785%	$127.9877	$127.99	$128.00	$128.00
Purchase #5	$186.87	7.335%	$200.5769	$200.58	$200.60	$200.60
Purchase #6	$250.33	4.192%	$260.8238	$260.82	$260.80	$260.80
Purchase #7	$141.98	10.486%	$156.868	$156.87	$156.85	$156.90
7 purchase totals =	$1,056.64		$1,136.3467	$1,136.36	$1,136.35	$1,136.40