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	$97.32	12.716%	$109.6952	$109.70	$109.70	$109.70
Purchase #2	$98.35	12.361%	$110.507	$110.51	$110.50	$110.50
Purchase #3	$13.73	4.665%	$14.3705	$14.37	$14.35	$14.40
Purchase #4	$240.75	9.697%	$264.0955	$264.10	$264.10	$264.10
Purchase #5	$165.67	11.505%	$184.7303	$184.73	$184.75	$184.70
Purchase #6	$116.78	8.836%	$127.0987	$127.10	$127.10	$127.10
Purchase #7	$249.44	10.477%	$275.5738	$275.57	$275.55	$275.60
7 purchase totals =	$982.04		$1,086.0710	$1,086.08	$1,086.05	$1,086.10