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	$128.64	3.163%	$132.7089	$132.71	$132.70	$132.70
Purchase #2	$157.27	6.792%	$167.9518	$167.95	$167.95	$168.00
Purchase #3	$105.81	3.737%	$109.7641	$109.76	$109.75	$109.80
Purchase #4	$188.89	4.249%	$196.9159	$196.92	$196.90	$196.90
Purchase #5	$176.67	13.115%	$199.8403	$199.84	$199.85	$199.80
Purchase #6	$200.28	10.593%	$221.4957	$221.50	$221.50	$221.50
Purchase #7	$129.64	11.351%	$144.3554	$144.36	$144.35	$144.40
7 purchase totals =	$1,087.20		$1,173.0321	$1,173.04	$1,173.00	$1,173.10