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	$165.92	4.838%	$173.9472	$173.95	$173.95	$173.90
Purchase #2	$246.97	3.139%	$254.7224	$254.72	$254.70	$254.70
Purchase #3	$105.85	7.710%	$114.011	$114.01	$114.00	$114.00
Purchase #4	$139.82	6.284%	$148.6063	$148.61	$148.60	$148.60
Purchase #5	$83.32	7.490%	$89.5607	$89.56	$89.55	$89.60
Purchase #6	$205.40	3.315%	$212.209	$212.21	$212.20	$212.20
Purchase #7	$164.61	7.239%	$176.5261	$176.53	$176.55	$176.50
7 purchase totals =	$1,111.89		$1,169.5827	$1,169.59	$1,169.55	$1,169.50