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	$196.65	6.821%	$210.0635	$210.06	$210.05	$210.10
Purchase #2	$22.86	6.349%	$24.3114	$24.31	$24.30	$24.30
Purchase #3	$127.25	5.447%	$134.1813	$134.18	$134.20	$134.20
Purchase #4	$31.61	10.102%	$34.8032	$34.80	$34.80	$34.80
Purchase #5	$150.69	11.651%	$168.2469	$168.25	$168.25	$168.20
Purchase #6	$224.71	13.215%	$254.4054	$254.41	$254.40	$254.40
Purchase #7	$157.77	11.861%	$176.4831	$176.48	$176.50	$176.50
7 purchase totals =	$911.54		$1,002.4948	$1,002.49	$1,002.50	$1,002.50