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	$126.58	10.781%	$140.2266	$140.23	$140.25	$140.20
Purchase #2	$21.43	5.611%	$22.6324	$22.63	$22.65	$22.60
Purchase #3	$37.48	5.569%	$39.5673	$39.57	$39.55	$39.60
Purchase #4	$148.36	13.408%	$168.2521	$168.25	$168.25	$168.30
Purchase #5	$157.64	4.619%	$164.9214	$164.92	$164.90	$164.90
Purchase #6	$62.57	6.650%	$66.7309	$66.73	$66.75	$66.70
Purchase #7	$82.26	11.706%	$91.8894	$91.89	$91.90	$91.90
7 purchase totals =	$636.32		$694.2201	$694.22	$694.25	$694.20