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	$182.72	9.803%	$200.632	$200.63	$200.65	$200.60
Purchase #2	$133.37	8.252%	$144.3757	$144.38	$144.40	$144.40
Purchase #3	$31.30	13.382%	$35.4886	$35.49	$35.50	$35.50
Purchase #4	$244.55	13.468%	$277.486	$277.49	$277.50	$277.50
Purchase #5	$210.36	9.500%	$230.3442	$230.34	$230.35	$230.30
Purchase #6	$18.55	3.119%	$19.1286	$19.13	$19.15	$19.10
Purchase #7	$133.37	12.790%	$150.428	$150.43	$150.45	$150.40
7 purchase totals =	$954.22		$1,057.8831	$1,057.89	$1,058.00	$1,057.80