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	$125.33	13.494%	$142.242	$142.24	$142.25	$142.20
Purchase #2	$234.50	3.477%	$242.6536	$242.65	$242.65	$242.70
Purchase #3	$32.67	3.682%	$33.8729	$33.87	$33.85	$33.90
Purchase #4	$138.53	9.826%	$152.142	$152.14	$152.15	$152.10
Purchase #5	$200.69	5.576%	$211.8805	$211.88	$211.90	$211.90
Purchase #6	$140.88	12.733%	$158.8183	$158.82	$158.80	$158.80
Purchase #7	$196.45	12.168%	$220.354	$220.35	$220.35	$220.40
7 purchase totals =	$1,069.05		$1,161.9633	$1,161.95	$1,161.95	$1,162.00