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	$82.28	3.836%	$85.4363	$85.44	$85.45	$85.40
Purchase #2	$41.51	8.411%	$45.0014	$45.00	$45.00	$45.00
Purchase #3	$120.90	6.803%	$129.1248	$129.12	$129.10	$129.10
Purchase #4	$30.97	12.809%	$34.9369	$34.94	$34.95	$34.90
Purchase #5	$175.96	11.720%	$196.5825	$196.58	$196.60	$196.60
Purchase #6	$228.45	11.227%	$254.0981	$254.10	$254.10	$254.10
Purchase #7	$211.82	4.721%	$221.82	$221.82	$221.80	$221.80
7 purchase totals =	$891.89		$967.0000	$967.00	$967.00	$966.90