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	$194.78	8.492%	$211.3207	$211.32	$211.30	$211.30
Purchase #2	$74.91	11.163%	$83.2722	$83.27	$83.25	$83.30
Purchase #3	$160.36	11.241%	$178.3861	$178.39	$178.40	$178.40
Purchase #4	$197.69	13.556%	$224.4889	$224.49	$224.50	$224.50
Purchase #5	$34.29	10.248%	$37.804	$37.80	$37.80	$37.80
Purchase #6	$205.48	4.821%	$215.3862	$215.39	$215.40	$215.40
Purchase #7	$196.64	11.127%	$218.5201	$218.52	$218.50	$218.50
7 purchase totals =	$1,064.15		$1,169.1782	$1,169.18	$1,169.15	$1,169.20