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	$191.34	9.335%	$209.2016	$209.20	$209.20	$209.20
Purchase #2	$101.60	10.153%	$111.9154	$111.92	$111.90	$111.90
Purchase #3	$171.49	8.127%	$185.427	$185.43	$185.45	$185.40
Purchase #4	$191.70	4.562%	$200.4454	$200.45	$200.45	$200.40
Purchase #5	$99.51	13.478%	$112.922	$112.92	$112.90	$112.90
Purchase #6	$43.88	4.722%	$45.952	$45.95	$45.95	$46.00
Purchase #7	$176.43	10.155%	$194.3465	$194.35	$194.35	$194.30
7 purchase totals =	$975.95		$1,060.2099	$1,060.22	$1,060.20	$1,060.10