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	$224.52	10.575%	$248.263	$248.26	$248.25	$248.30
Purchase #2	$182.63	9.208%	$199.4466	$199.45	$199.45	$199.40
Purchase #3	$168.89	11.232%	$187.8597	$187.86	$187.85	$187.90
Purchase #4	$33.93	9.379%	$37.1123	$37.11	$37.10	$37.10
Purchase #5	$32.93	8.570%	$35.7521	$35.75	$35.75	$35.80
Purchase #6	$248.71	12.794%	$280.53	$280.53	$280.55	$280.50
Purchase #7	$71.66	7.766%	$77.2251	$77.23	$77.25	$77.20
7 purchase totals =	$963.27		$1,066.1888	$1,066.19	$1,066.20	$1,066.20