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	$161.69	10.129%	$178.0676	$178.07	$178.05	$178.10
Purchase #2	$77.38	13.782%	$88.0445	$88.04	$88.05	$88.00
Purchase #3	$166.32	3.634%	$172.3641	$172.36	$172.35	$172.40
Purchase #4	$35.55	8.179%	$38.4576	$38.46	$38.45	$38.50
Purchase #5	$58.84	4.471%	$61.4707	$61.47	$61.45	$61.50
Purchase #6	$185.25	6.554%	$197.3913	$197.39	$197.40	$197.40
Purchase #7	$178.55	10.163%	$196.696	$196.70	$196.70	$196.70
7 purchase totals =	$863.58		$932.4918	$932.49	$932.45	$932.60