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	$210.72	6.231%	$223.85	$223.85	$223.85	$223.90
Purchase #2	$89.82	6.799%	$95.9269	$95.93	$95.95	$95.90
Purchase #3	$153.80	10.388%	$169.7767	$169.78	$169.80	$169.80
Purchase #4	$24.86	4.367%	$25.9456	$25.95	$25.95	$25.90
Purchase #5	$250.39	4.580%	$261.8579	$261.86	$261.85	$261.90
Purchase #6	$93.40	7.592%	$100.4909	$100.49	$100.50	$100.50
Purchase #7	$195.30	6.543%	$208.0785	$208.08	$208.10	$208.10
7 purchase totals =	$1,018.29		$1,085.9265	$1,085.94	$1,086.00	$1,086.00