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	$195.83	10.339%	$216.0769	$216.08	$216.10	$216.10
Purchase #2	$161.83	3.793%	$167.9682	$167.97	$167.95	$168.00
Purchase #3	$47.38	5.144%	$49.8172	$49.82	$49.80	$49.80
Purchase #4	$72.88	13.296%	$82.5701	$82.57	$82.55	$82.60
Purchase #5	$113.94	11.420%	$126.9519	$126.95	$126.95	$127.00
Purchase #6	$236.45	7.135%	$253.3207	$253.32	$253.30	$253.30
Purchase #7	$152.78	7.610%	$164.4066	$164.41	$164.40	$164.40
7 purchase totals =	$981.09		$1,061.1116	$1,061.12	$1,061.05	$1,061.20