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	$59.73	9.596%	$65.4617	$65.46	$65.45	$65.50
Purchase #2	$164.95	12.622%	$185.77	$185.77	$185.75	$185.80
Purchase #3	$126.89	3.736%	$131.6306	$131.63	$131.65	$131.60
Purchase #4	$119.91	3.342%	$123.9174	$123.92	$123.90	$123.90
Purchase #5	$122.56	3.303%	$126.6082	$126.61	$126.60	$126.60
Purchase #6	$146.74	9.143%	$160.1564	$160.16	$160.15	$160.20
Purchase #7	$194.95	11.582%	$217.5291	$217.53	$217.55	$217.50
7 purchase totals =	$935.73		$1,011.0734	$1,011.08	$1,011.05	$1,011.10