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	$238.41	8.849%	$259.5069	$259.51	$259.50	$259.50
Purchase #2	$59.97	13.107%	$67.8303	$67.83	$67.85	$67.80
Purchase #3	$120.77	5.411%	$127.3049	$127.30	$127.30	$127.30
Purchase #4	$136.90	3.375%	$141.5204	$141.52	$141.50	$141.50
Purchase #5	$141.74	10.865%	$157.1401	$157.14	$157.15	$157.10
Purchase #6	$95.39	4.839%	$100.0059	$100.01	$100.00	$100.00
Purchase #7	$162.43	6.283%	$172.6355	$172.64	$172.65	$172.60
7 purchase totals =	$955.61		$1,025.9440	$1,025.95	$1,025.95	$1,025.80