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	$169.34	12.821%	$191.0511	$191.05	$191.05	$191.10
Purchase #2	$230.64	7.767%	$248.5538	$248.55	$248.55	$248.60
Purchase #3	$237.63	7.340%	$255.072	$255.07	$255.05	$255.10
Purchase #4	$52.64	13.513%	$59.7532	$59.75	$59.75	$59.80
Purchase #5	$69.85	12.469%	$78.5596	$78.56	$78.55	$78.60
Purchase #6	$42.26	9.387%	$46.2269	$46.23	$46.25	$46.20
Purchase #7	$163.51	12.210%	$183.4746	$183.47	$183.45	$183.50
7 purchase totals =	$965.87		$1,062.6912	$1,062.68	$1,062.65	$1,062.90