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	$177.38	5.755%	$187.5882	$187.59	$187.60	$187.60
Purchase #2	$174.74	12.170%	$196.0059	$196.01	$196.00	$196.00
Purchase #3	$153.58	8.651%	$166.8662	$166.87	$166.85	$166.90
Purchase #4	$81.26	12.146%	$91.1298	$91.13	$91.15	$91.10
Purchase #5	$78.90	5.149%	$82.9626	$82.96	$82.95	$83.00
Purchase #6	$175.90	10.685%	$194.6949	$194.69	$194.70	$194.70
Purchase #7	$193.81	5.422%	$204.3184	$204.32	$204.30	$204.30
7 purchase totals =	$1,035.57		$1,123.5660	$1,123.57	$1,123.55	$1,123.60