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	$62.32	10.317%	$68.7496	$68.75	$68.75	$68.70
Purchase #2	$61.77	5.119%	$64.932	$64.93	$64.95	$64.90
Purchase #3	$173.79	9.429%	$190.1767	$190.18	$190.20	$190.20
Purchase #4	$98.58	7.377%	$105.8522	$105.85	$105.85	$105.90
Purchase #5	$241.68	12.497%	$271.8827	$271.88	$271.90	$271.90
Purchase #6	$220.61	4.766%	$231.1243	$231.12	$231.10	$231.10
Purchase #7	$113.53	12.304%	$127.4987	$127.50	$127.50	$127.50
7 purchase totals =	$972.28		$1,060.2162	$1,060.21	$1,060.25	$1,060.20