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	$135.25	11.598%	$150.9363	$150.94	$150.95	$150.90
Purchase #2	$167.94	9.352%	$183.6457	$183.65	$183.65	$183.60
Purchase #3	$12.59	12.361%	$14.1462	$14.15	$14.15	$14.10
Purchase #4	$146.50	4.464%	$153.0398	$153.04	$153.05	$153.00
Purchase #5	$31.25	12.448%	$35.14	$35.14	$35.15	$35.10
Purchase #6	$61.72	7.560%	$66.386	$66.39	$66.40	$66.40
Purchase #7	$157.29	3.300%	$162.4806	$162.48	$162.50	$162.50
7 purchase totals =	$712.54		$765.7746	$765.79	$765.85	$765.60