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	$180.59	8.559%	$196.0467	$196.05	$196.05	$196.00
Purchase #2	$141.47	12.322%	$158.9019	$158.90	$158.90	$158.90
Purchase #3	$152.30	11.730%	$170.1648	$170.16	$170.15	$170.20
Purchase #4	$113.64	3.208%	$117.2856	$117.29	$117.30	$117.30
Purchase #5	$155.42	4.142%	$161.8575	$161.86	$161.85	$161.90
Purchase #6	$200.73	6.435%	$213.647	$213.65	$213.65	$213.60
Purchase #7	$37.49	12.679%	$42.2434	$42.24	$42.25	$42.20
7 purchase totals =	$981.64		$1,060.1469	$1,060.15	$1,060.15	$1,060.10