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	$162.31	12.710%	$182.9396	$182.94	$182.95	$182.90
Purchase #2	$162.78	3.651%	$168.7231	$168.72	$168.70	$168.70
Purchase #3	$161.35	11.325%	$179.6229	$179.62	$179.60	$179.60
Purchase #4	$105.44	12.226%	$118.3311	$118.33	$118.35	$118.30
Purchase #5	$143.53	11.651%	$160.2527	$160.25	$160.25	$160.30
Purchase #6	$179.87	7.512%	$193.3818	$193.38	$193.40	$193.40
Purchase #7	$180.95	8.733%	$196.7524	$196.75	$196.75	$196.80
7 purchase totals =	$1,096.23		$1,200.0036	$1,199.99	$1,200.00	$1,200.00