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	$112.25	4.657%	$117.4775	$117.48	$117.50	$117.50
Purchase #2	$132.38	10.555%	$146.3527	$146.35	$146.35	$146.40
Purchase #3	$137.43	12.481%	$154.5826	$154.58	$154.60	$154.60
Purchase #4	$233.81	3.231%	$241.3644	$241.36	$241.35	$241.40
Purchase #5	$152.91	12.285%	$171.695	$171.70	$171.70	$171.70
Purchase #6	$168.74	8.149%	$182.4906	$182.49	$182.50	$182.50
Purchase #7	$153.92	9.479%	$168.5101	$168.51	$168.50	$168.50
7 purchase totals =	$1,091.44		$1,182.4729	$1,182.47	$1,182.50	$1,182.60