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	$202.26	10.193%	$222.8764	$222.88	$222.90	$222.90
Purchase #2	$20.76	8.783%	$22.5834	$22.58	$22.60	$22.60
Purchase #3	$80.29	5.250%	$84.5052	$84.51	$84.50	$84.50
Purchase #4	$128.87	11.456%	$143.6333	$143.63	$143.65	$143.60
Purchase #5	$178.64	11.119%	$198.503	$198.50	$198.50	$198.50
Purchase #6	$12.89	10.818%	$14.2844	$14.28	$14.30	$14.30
Purchase #7	$69.89	12.597%	$78.694	$78.69	$78.70	$78.70
7 purchase totals =	$693.60		$765.0797	$765.07	$765.15	$765.10