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	$173.62	9.625%	$190.3309	$190.33	$190.35	$190.30
Purchase #2	$11.96	7.834%	$12.8969	$12.90	$12.90	$12.90
Purchase #3	$125.66	5.805%	$132.9546	$132.95	$132.95	$133.00
Purchase #4	$126.66	11.628%	$141.388	$141.39	$141.40	$141.40
Purchase #5	$173.39	10.508%	$191.6098	$191.61	$191.60	$191.60
Purchase #6	$68.75	6.678%	$73.3411	$73.34	$73.35	$73.30
Purchase #7	$42.94	3.442%	$44.418	$44.42	$44.40	$44.40
7 purchase totals =	$722.98		$786.9393	$786.94	$786.95	$786.90