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	$174.35	13.612%	$198.0825	$198.08	$198.10	$198.10
Purchase #2	$148.41	10.602%	$164.1444	$164.14	$164.15	$164.10
Purchase #3	$44.89	4.356%	$46.8454	$46.85	$46.85	$46.80
Purchase #4	$95.30	10.679%	$105.4771	$105.48	$105.50	$105.50
Purchase #5	$114.29	11.123%	$127.0025	$127.00	$127.00	$127.00
Purchase #6	$239.47	9.504%	$262.2292	$262.23	$262.25	$262.20
Purchase #7	$138.71	6.779%	$148.1132	$148.11	$148.10	$148.10
7 purchase totals =	$955.42		$1,051.8943	$1,051.89	$1,051.95	$1,051.80