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	$164.48	11.478%	$183.359	$183.36	$183.35	$183.40
Purchase #2	$221.99	4.726%	$232.4812	$232.48	$232.50	$232.50
Purchase #3	$174.79	3.744%	$181.3341	$181.33	$181.35	$181.30
Purchase #4	$117.33	13.202%	$132.8199	$132.82	$132.80	$132.80
Purchase #5	$128.59	12.645%	$144.8502	$144.85	$144.85	$144.90
Purchase #6	$112.67	3.748%	$116.8929	$116.89	$116.90	$116.90
Purchase #7	$36.71	12.721%	$41.3799	$41.38	$41.40	$41.40
7 purchase totals =	$956.56		$1,033.1172	$1,033.11	$1,033.15	$1,033.20