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	$248.57	5.534%	$262.3259	$262.33	$262.35	$262.30
Purchase #2	$137.84	5.615%	$145.5797	$145.58	$145.60	$145.60
Purchase #3	$161.71	10.150%	$178.1236	$178.12	$178.10	$178.10
Purchase #4	$60.89	9.237%	$66.5144	$66.51	$66.50	$66.50
Purchase #5	$78.56	8.333%	$85.1064	$85.11	$85.10	$85.10
Purchase #6	$12.29	13.488%	$13.9477	$13.95	$13.95	$13.90
Purchase #7	$70.36	4.734%	$73.6908	$73.69	$73.70	$73.70
7 purchase totals =	$770.22		$825.2885	$825.29	$825.30	$825.20