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	$182.87	7.318%	$196.2524	$196.25	$196.25	$196.30
Purchase #2	$66.58	10.652%	$73.6721	$73.67	$73.65	$73.70
Purchase #3	$166.28	4.791%	$174.2465	$174.25	$174.25	$174.20
Purchase #4	$179.78	4.725%	$188.2746	$188.27	$188.25	$188.30
Purchase #5	$50.81	6.293%	$54.0075	$54.01	$54.00	$54.00
Purchase #6	$230.25	4.625%	$240.8991	$240.90	$240.90	$240.90
Purchase #7	$135.55	6.545%	$144.4217	$144.42	$144.40	$144.40
7 purchase totals =	$1,012.12		$1,071.7739	$1,071.77	$1,071.70	$1,071.80