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	$140.31	11.142%	$155.9433	$155.94	$155.95	$155.90
Purchase #2	$231.63	8.209%	$250.6445	$250.64	$250.65	$250.60
Purchase #3	$56.25	5.689%	$59.4501	$59.45	$59.45	$59.50
Purchase #4	$88.94	6.808%	$94.995	$95.00	$95.00	$95.00
Purchase #5	$213.86	3.804%	$221.9952	$222.00	$222.00	$222.00
Purchase #6	$178.44	12.202%	$200.2132	$200.21	$200.20	$200.20
Purchase #7	$107.95	4.589%	$112.9038	$112.90	$112.90	$112.90
7 purchase totals =	$1,017.38		$1,096.1451	$1,096.14	$1,096.15	$1,096.10