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	$62.66	11.231%	$69.6973	$69.70	$69.70	$69.70
Purchase #2	$35.84	3.421%	$37.0661	$37.07	$37.05	$37.10
Purchase #3	$249.64	3.374%	$258.0629	$258.06	$258.05	$258.10
Purchase #4	$50.98	6.239%	$54.1606	$54.16	$54.15	$54.20
Purchase #5	$242.46	5.743%	$256.3845	$256.38	$256.40	$256.40
Purchase #6	$210.83	6.501%	$224.5361	$224.54	$224.55	$224.50
Purchase #7	$150.26	12.169%	$168.5451	$168.55	$168.55	$168.50
7 purchase totals =	$1,002.67		$1,068.4526	$1,068.46	$1,068.45	$1,068.50