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	$78.26	4.719%	$81.9531	$81.95	$81.95	$82.00
Purchase #2	$30.67	5.264%	$32.2845	$32.28	$32.30	$32.30
Purchase #3	$90.28	6.400%	$96.0579	$96.06	$96.05	$96.10
Purchase #4	$97.85	13.600%	$111.1576	$111.16	$111.15	$111.20
Purchase #5	$20.59	10.534%	$22.759	$22.76	$22.75	$22.80
Purchase #6	$13.66	3.578%	$14.1488	$14.15	$14.15	$14.10
Purchase #7	$160.57	13.752%	$182.6516	$182.65	$182.65	$182.70
7 purchase totals =	$491.88		$541.0125	$541.01	$541.00	$541.20