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	$215.86	3.364%	$223.1215	$223.12	$223.10	$223.10
Purchase #2	$10.27	3.735%	$10.6536	$10.65	$10.65	$10.70
Purchase #3	$236.74	8.545%	$256.9694	$256.97	$256.95	$257.00
Purchase #4	$100.44	9.453%	$109.9346	$109.93	$109.95	$109.90
Purchase #5	$41.32	12.500%	$46.485	$46.49	$46.50	$46.50
Purchase #6	$248.35	7.729%	$267.545	$267.55	$267.55	$267.50
Purchase #7	$205.32	3.682%	$212.8799	$212.88	$212.90	$212.90
7 purchase totals =	$1,058.30		$1,127.5890	$1,127.59	$1,127.60	$1,127.60