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	$95.82	11.635%	$106.9687	$106.97	$106.95	$107.00
Purchase #2	$156.56	5.294%	$164.8483	$164.85	$164.85	$164.80
Purchase #3	$152.60	9.752%	$167.4816	$167.48	$167.50	$167.50
Purchase #4	$138.80	12.756%	$156.5053	$156.51	$156.50	$156.50
Purchase #5	$109.32	3.409%	$113.0467	$113.05	$113.05	$113.00
Purchase #6	$127.39	7.678%	$137.171	$137.17	$137.15	$137.20
Purchase #7	$146.69	8.170%	$158.6746	$158.67	$158.65	$158.70
7 purchase totals =	$927.18		$1,004.6962	$1,004.70	$1,004.65	$1,004.70