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	$83.62	3.403%	$86.4656	$86.47	$86.45	$86.50
Purchase #2	$78.93	8.394%	$85.5554	$85.56	$85.55	$85.60
Purchase #3	$20.94	5.862%	$22.1675	$22.17	$22.15	$22.20
Purchase #4	$102.44	3.786%	$106.3184	$106.32	$106.30	$106.30
Purchase #5	$169.92	13.451%	$192.7759	$192.78	$192.80	$192.80
Purchase #6	$227.77	13.758%	$259.1066	$259.11	$259.10	$259.10
Purchase #7	$179.43	9.746%	$196.9172	$196.92	$196.90	$196.90
7 purchase totals =	$863.05		$949.3066	$949.33	$949.25	$949.40