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	$184.43	6.250%	$195.9569	$195.96	$195.95	$196.00
Purchase #2	$6.59	13.421%	$7.4744	$7.47	$7.45	$7.50
Purchase #3	$73.31	12.673%	$82.6006	$82.60	$82.60	$82.60
Purchase #4	$203.56	10.459%	$224.8503	$224.85	$224.85	$224.90
Purchase #5	$186.51	5.392%	$196.5666	$196.57	$196.55	$196.60
Purchase #6	$111.31	9.526%	$121.9134	$121.91	$121.90	$121.90
Purchase #7	$131.75	8.503%	$142.9527	$142.95	$142.95	$143.00
7 purchase totals =	$897.46		$972.3149	$972.31	$972.25	$972.50