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	$86.62	10.710%	$95.897	$95.90	$95.90	$95.90
Purchase #2	$148.44	5.172%	$156.1173	$156.12	$156.10	$156.10
Purchase #3	$89.85	13.607%	$102.0759	$102.08	$102.10	$102.10
Purchase #4	$150.27	4.501%	$157.0337	$157.03	$157.05	$157.00
Purchase #5	$131.37	8.268%	$142.2317	$142.23	$142.25	$142.20
Purchase #6	$144.33	13.785%	$164.2259	$164.23	$164.25	$164.20
Purchase #7	$247.84	10.111%	$272.8991	$272.90	$272.90	$272.90
7 purchase totals =	$998.72		$1,090.4806	$1,090.49	$1,090.55	$1,090.40