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	$207.68	10.620%	$229.7356	$229.74	$229.75	$229.70
Purchase #2	$32.32	8.870%	$35.1868	$35.19	$35.20	$35.20
Purchase #3	$44.98	9.792%	$49.3844	$49.38	$49.40	$49.40
Purchase #4	$164.83	4.553%	$172.3347	$172.33	$172.35	$172.30
Purchase #5	$229.58	3.190%	$236.9036	$236.90	$236.90	$236.90
Purchase #6	$101.30	9.577%	$111.0015	$111.00	$111.00	$111.00
Purchase #7	$176.66	4.599%	$184.7846	$184.78	$184.80	$184.80
7 purchase totals =	$957.35		$1,019.3312	$1,019.32	$1,019.40	$1,019.30