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	$192.83	10.491%	$213.0598	$213.06	$213.05	$213.10
Purchase #2	$101.95	9.759%	$111.8993	$111.90	$111.90	$111.90
Purchase #3	$85.40	12.691%	$96.2381	$96.24	$96.25	$96.20
Purchase #4	$5.44	3.430%	$5.6266	$5.63	$5.65	$5.60
Purchase #5	$72.29	8.527%	$78.4542	$78.45	$78.45	$78.50
Purchase #6	$180.67	8.734%	$196.4497	$196.45	$196.45	$196.40
Purchase #7	$61.94	5.676%	$65.4557	$65.46	$65.45	$65.50
7 purchase totals =	$700.52		$767.1834	$767.19	$767.20	$767.20