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	$161.82	12.139%	$181.4633	$181.46	$181.45	$181.50
Purchase #2	$9.44	7.484%	$10.1465	$10.15	$10.15	$10.10
Purchase #3	$142.90	10.507%	$157.9145	$157.91	$157.90	$157.90
Purchase #4	$123.60	6.112%	$131.1544	$131.15	$131.15	$131.20
Purchase #5	$112.92	11.665%	$126.0921	$126.09	$126.10	$126.10
Purchase #6	$25.31	4.595%	$26.473	$26.47	$26.45	$26.50
Purchase #7	$110.62	11.494%	$123.3347	$123.33	$123.35	$123.30
7 purchase totals =	$686.61		$756.5785	$756.56	$756.55	$756.60