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	$41.37	8.687%	$44.9638	$44.96	$44.95	$45.00
Purchase #2	$81.29	7.194%	$87.138	$87.14	$87.15	$87.10
Purchase #3	$36.90	9.572%	$40.4321	$40.43	$40.45	$40.40
Purchase #4	$96.44	3.737%	$100.044	$100.04	$100.05	$100.00
Purchase #5	$173.49	5.466%	$182.973	$182.97	$182.95	$183.00
Purchase #6	$189.78	11.423%	$211.4586	$211.46	$211.45	$211.50
Purchase #7	$90.34	6.134%	$95.8815	$95.88	$95.90	$95.90
7 purchase totals =	$709.61		$762.8910	$762.88	$762.90	$762.90