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	$148.59	5.262%	$156.4088	$156.41	$156.40	$156.40
Purchase #2	$94.50	11.307%	$105.1851	$105.19	$105.20	$105.20
Purchase #3	$150.28	12.260%	$168.7043	$168.70	$168.70	$168.70
Purchase #4	$175.55	4.400%	$183.2742	$183.27	$183.25	$183.30
Purchase #5	$125.38	13.676%	$142.527	$142.53	$142.55	$142.50
Purchase #6	$241.52	5.206%	$254.0935	$254.09	$254.10	$254.10
Purchase #7	$14.40	5.241%	$15.1547	$15.15	$15.15	$15.20
7 purchase totals =	$950.22		$1,025.3476	$1,025.34	$1,025.35	$1,025.40