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	$196.69	6.197%	$208.8789	$208.88	$208.90	$208.90
Purchase #2	$167.90	8.743%	$182.5795	$182.58	$182.60	$182.60
Purchase #3	$107.79	3.774%	$111.858	$111.86	$111.85	$111.90
Purchase #4	$185.46	6.514%	$197.5409	$197.54	$197.55	$197.50
Purchase #5	$222.69	11.579%	$248.4753	$248.48	$248.50	$248.50
Purchase #6	$181.82	10.301%	$200.5493	$200.55	$200.55	$200.50
Purchase #7	$194.83	8.854%	$212.0802	$212.08	$212.10	$212.10
7 purchase totals =	$1,257.18		$1,361.9621	$1,361.97	$1,362.05	$1,362.00