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	$101.32	3.455%	$104.8206	$104.82	$104.80	$104.80
Purchase #2	$10.90	5.460%	$11.4951	$11.50	$11.50	$11.50
Purchase #3	$143.36	10.429%	$158.311	$158.31	$158.30	$158.30
Purchase #4	$159.46	3.187%	$164.542	$164.54	$164.55	$164.50
Purchase #5	$47.93	6.198%	$50.9007	$50.90	$50.90	$50.90
Purchase #6	$169.89	11.270%	$189.0366	$189.04	$189.05	$189.00
Purchase #7	$250.57	7.593%	$269.5958	$269.60	$269.60	$269.60
7 purchase totals =	$883.43		$948.7018	$948.71	$948.70	$948.60