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	$184.63	8.469%	$200.2663	$200.27	$200.25	$200.30
Purchase #2	$196.86	13.769%	$223.9657	$223.97	$223.95	$224.00
Purchase #3	$31.26	13.225%	$35.3941	$35.39	$35.40	$35.40
Purchase #4	$177.45	12.833%	$200.2222	$200.22	$200.20	$200.20
Purchase #5	$93.95	12.245%	$105.4542	$105.45	$105.45	$105.50
Purchase #6	$111.59	5.196%	$117.3882	$117.39	$117.40	$117.40
Purchase #7	$230.25	13.236%	$260.7259	$260.73	$260.75	$260.70
7 purchase totals =	$1,025.99		$1,143.4166	$1,143.42	$1,143.40	$1,143.50