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	$102.26	8.793%	$111.2517	$111.25	$111.25	$111.30
Purchase #2	$175.57	11.698%	$196.1082	$196.11	$196.10	$196.10
Purchase #3	$230.48	6.234%	$244.8481	$244.85	$244.85	$244.80
Purchase #4	$131.75	5.315%	$138.7525	$138.75	$138.75	$138.80
Purchase #5	$99.95	3.406%	$103.3543	$103.35	$103.35	$103.40
Purchase #6	$164.49	7.271%	$176.4501	$176.45	$176.45	$176.50
Purchase #7	$163.82	11.527%	$182.7035	$182.70	$182.70	$182.70
7 purchase totals =	$1,068.32		$1,153.4684	$1,153.46	$1,153.45	$1,153.60