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	$208.72	11.738%	$233.2196	$233.22	$233.20	$233.20
Purchase #2	$195.87	8.833%	$213.1712	$213.17	$213.15	$213.20
Purchase #3	$172.78	3.478%	$178.7893	$178.79	$178.80	$178.80
Purchase #4	$184.97	13.225%	$209.4323	$209.43	$209.45	$209.40
Purchase #5	$9.73	9.838%	$10.6872	$10.69	$10.70	$10.70
Purchase #6	$56.76	8.425%	$61.542	$61.54	$61.55	$61.50
Purchase #7	$176.91	4.829%	$185.453	$185.45	$185.45	$185.50
7 purchase totals =	$1,005.74		$1,092.2946	$1,092.29	$1,092.30	$1,092.30