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	$173.25	13.428%	$196.514	$196.51	$196.50	$196.50
Purchase #2	$20.86	5.517%	$22.0108	$22.01	$22.00	$22.00
Purchase #3	$46.65	10.369%	$51.4871	$51.49	$51.50	$51.50
Purchase #4	$22.37	13.683%	$25.4309	$25.43	$25.45	$25.40
Purchase #5	$167.43	9.253%	$182.9223	$182.92	$182.90	$182.90
Purchase #6	$216.88	6.479%	$230.9317	$230.93	$230.95	$230.90
Purchase #7	$216.43	12.728%	$243.9772	$243.98	$244.00	$244.00
7 purchase totals =	$863.87		$953.2740	$953.27	$953.30	$953.20