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	$171.39	11.369%	$190.8753	$190.88	$190.90	$190.90
Purchase #2	$159.45	8.465%	$172.9474	$172.95	$172.95	$172.90
Purchase #3	$164.67	7.372%	$176.8095	$176.81	$176.80	$176.80
Purchase #4	$174.57	7.782%	$188.155	$188.16	$188.15	$188.20
Purchase #5	$207.57	3.356%	$214.536	$214.54	$214.55	$214.50
Purchase #6	$9.83	7.317%	$10.5493	$10.55	$10.55	$10.50
Purchase #7	$110.94	11.599%	$123.8079	$123.81	$123.80	$123.80
7 purchase totals =	$998.42		$1,077.6804	$1,077.70	$1,077.70	$1,077.60