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	$65.61	10.211%	$72.3094	$72.31	$72.30	$72.30
Purchase #2	$161.59	12.176%	$181.2652	$181.27	$181.25	$181.30
Purchase #3	$162.82	5.301%	$171.4511	$171.45	$171.45	$171.50
Purchase #4	$10.58	3.604%	$10.9613	$10.96	$10.95	$11.00
Purchase #5	$241.77	13.271%	$273.8553	$273.86	$273.85	$273.90
Purchase #6	$197.93	5.128%	$208.0799	$208.08	$208.10	$208.10
Purchase #7	$156.44	5.135%	$164.4732	$164.47	$164.45	$164.50
7 purchase totals =	$996.74		$1,082.3954	$1,082.40	$1,082.35	$1,082.60