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	$62.56	7.789%	$67.4328	$67.43	$67.45	$67.40
Purchase #2	$213.36	4.291%	$222.5153	$222.52	$222.50	$222.50
Purchase #3	$86.65	13.402%	$98.2628	$98.26	$98.25	$98.30
Purchase #4	$113.46	12.735%	$127.9091	$127.91	$127.90	$127.90
Purchase #5	$200.58	8.399%	$217.4267	$217.43	$217.45	$217.40
Purchase #6	$130.66	13.872%	$148.7852	$148.79	$148.80	$148.80
Purchase #7	$139.36	7.748%	$150.1576	$150.16	$150.15	$150.20
7 purchase totals =	$946.63		$1,032.4895	$1,032.50	$1,032.50	$1,032.50