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	$213.38	12.870%	$240.842	$240.84	$240.85	$240.80
Purchase #2	$42.64	4.102%	$44.3891	$44.39	$44.40	$44.40
Purchase #3	$53.27	3.529%	$55.1499	$55.15	$55.15	$55.10
Purchase #4	$239.82	5.752%	$253.6144	$253.61	$253.60	$253.60
Purchase #5	$173.86	7.768%	$187.3654	$187.37	$187.35	$187.40
Purchase #6	$143.39	10.608%	$158.6008	$158.60	$158.60	$158.60
Purchase #7	$201.90	5.163%	$212.3241	$212.32	$212.30	$212.30
7 purchase totals =	$1,068.26		$1,152.2857	$1,152.28	$1,152.25	$1,152.20