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	$191.25	12.163%	$214.5117	$214.51	$214.50	$214.50
Purchase #2	$12.59	10.442%	$13.9046	$13.90	$13.90	$13.90
Purchase #3	$43.38	13.749%	$49.3443	$49.34	$49.35	$49.30
Purchase #4	$100.63	11.183%	$111.8835	$111.88	$111.90	$111.90
Purchase #5	$233.98	13.121%	$264.6805	$264.68	$264.70	$264.70
Purchase #6	$171.76	9.759%	$188.5221	$188.52	$188.50	$188.50
Purchase #7	$158.54	4.218%	$165.2272	$165.23	$165.25	$165.20
7 purchase totals =	$912.13		$1,008.0739	$1,008.06	$1,008.10	$1,008.00