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	$130.48	11.416%	$145.3756	$145.38	$145.40	$145.40
Purchase #2	$29.72	10.513%	$32.8445	$32.84	$32.85	$32.80
Purchase #3	$47.44	11.638%	$52.9611	$52.96	$52.95	$53.00
Purchase #4	$82.77	11.803%	$92.5393	$92.54	$92.55	$92.50
Purchase #5	$60.54	6.336%	$64.3758	$64.38	$64.40	$64.40
Purchase #6	$27.47	3.391%	$28.4015	$28.40	$28.40	$28.40
Purchase #7	$47.54	10.769%	$52.6596	$52.66	$52.65	$52.70
7 purchase totals =	$425.96		$469.1574	$469.16	$469.20	$469.20