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	$183.40	7.122%	$196.4617	$196.46	$196.45	$196.50
Purchase #2	$170.83	12.166%	$191.6132	$191.61	$191.60	$191.60
Purchase #3	$15.67	11.783%	$17.5164	$17.52	$17.50	$17.50
Purchase #4	$140.67	8.228%	$152.2443	$152.24	$152.25	$152.20
Purchase #5	$160.73	13.552%	$182.5121	$182.51	$182.50	$182.50
Purchase #6	$134.70	9.814%	$147.9195	$147.92	$147.90	$147.90
Purchase #7	$102.51	13.696%	$116.5498	$116.55	$116.55	$116.50
7 purchase totals =	$908.51		$1,004.8170	$1,004.81	$1,004.75	$1,004.70