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	$179.66	12.807%	$202.6691	$202.67	$202.65	$202.70
Purchase #2	$72.94	13.798%	$83.0043	$83.00	$83.00	$83.00
Purchase #3	$104.42	12.532%	$117.5059	$117.51	$117.50	$117.50
Purchase #4	$236.31	8.406%	$256.1742	$256.17	$256.15	$256.20
Purchase #5	$175.29	3.430%	$181.3024	$181.30	$181.30	$181.30
Purchase #6	$166.78	12.349%	$187.3757	$187.38	$187.40	$187.40
Purchase #7	$80.91	3.119%	$83.4336	$83.43	$83.45	$83.40
7 purchase totals =	$1,016.31		$1,111.4652	$1,111.46	$1,111.45	$1,111.50