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	$190.95	6.138%	$202.6705	$202.67	$202.65	$202.70
Purchase #2	$141.35	6.471%	$150.4968	$150.50	$150.50	$150.50
Purchase #3	$122.48	5.198%	$128.8465	$128.85	$128.85	$128.80
Purchase #4	$137.88	13.667%	$156.7241	$156.72	$156.70	$156.70
Purchase #5	$95.55	11.494%	$106.5325	$106.53	$106.55	$106.50
Purchase #6	$119.34	6.781%	$127.4324	$127.43	$127.45	$127.40
Purchase #7	$155.99	5.722%	$164.9157	$164.92	$164.90	$164.90
7 purchase totals =	$963.54		$1,037.6185	$1,037.62	$1,037.60	$1,037.50