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	$166.94	8.680%	$181.4304	$181.43	$181.45	$181.40
Purchase #2	$65.39	10.783%	$72.441	$72.44	$72.45	$72.40
Purchase #3	$189.90	8.671%	$206.3662	$206.37	$206.35	$206.40
Purchase #4	$94.99	8.748%	$103.2997	$103.30	$103.30	$103.30
Purchase #5	$104.28	13.517%	$118.3755	$118.38	$118.40	$118.40
Purchase #6	$172.78	6.375%	$183.7947	$183.79	$183.80	$183.80
Purchase #7	$156.95	9.142%	$171.2984	$171.30	$171.30	$171.30
7 purchase totals =	$951.23		$1,037.0059	$1,037.01	$1,037.05	$1,037.00