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	$118.30	7.409%	$127.0648	$127.06	$127.05	$127.10
Purchase #2	$184.96	7.163%	$198.2087	$198.21	$198.20	$198.20
Purchase #3	$164.74	3.870%	$171.1154	$171.12	$171.10	$171.10
Purchase #4	$20.63	8.317%	$22.3458	$22.35	$22.35	$22.30
Purchase #5	$243.86	4.685%	$255.2848	$255.28	$255.30	$255.30
Purchase #6	$214.71	11.747%	$239.932	$239.93	$239.95	$239.90
Purchase #7	$226.58	12.756%	$255.4825	$255.48	$255.50	$255.50
7 purchase totals =	$1,173.78		$1,269.4340	$1,269.43	$1,269.45	$1,269.40