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	$77.37	11.178%	$86.0184	$86.02	$86.00	$86.00
Purchase #2	$102.55	10.195%	$113.005	$113.01	$113.00	$113.00
Purchase #3	$131.90	4.499%	$137.8342	$137.83	$137.85	$137.80
Purchase #4	$201.71	4.406%	$210.5973	$210.60	$210.60	$210.60
Purchase #5	$247.82	12.456%	$278.6885	$278.69	$278.70	$278.70
Purchase #6	$155.60	12.404%	$174.9006	$174.90	$174.90	$174.90
Purchase #7	$78.77	4.707%	$82.4777	$82.48	$82.50	$82.50
7 purchase totals =	$995.72		$1,083.5217	$1,083.53	$1,083.55	$1,083.50