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	$155.81	4.208%	$162.3665	$162.37	$162.35	$162.40
Purchase #2	$30.91	5.671%	$32.6629	$32.66	$32.65	$32.70
Purchase #3	$147.98	5.598%	$156.2639	$156.26	$156.25	$156.30
Purchase #4	$30.41	11.404%	$33.878	$33.88	$33.90	$33.90
Purchase #5	$30.96	6.107%	$32.8507	$32.85	$32.85	$32.90
Purchase #6	$187.92	5.119%	$197.5396	$197.54	$197.55	$197.50
Purchase #7	$129.71	11.310%	$144.3802	$144.38	$144.40	$144.40
7 purchase totals =	$713.70		$759.9418	$759.94	$759.95	$760.10