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	$122.57	4.310%	$127.8528	$127.85	$127.85	$127.90
Purchase #2	$173.82	13.214%	$196.7886	$196.79	$196.80	$196.80
Purchase #3	$55.46	10.457%	$61.2595	$61.26	$61.25	$61.30
Purchase #4	$133.53	5.264%	$140.559	$140.56	$140.55	$140.60
Purchase #5	$171.32	9.505%	$187.604	$187.60	$187.60	$187.60
Purchase #6	$185.45	11.273%	$206.3558	$206.36	$206.35	$206.40
Purchase #7	$81.25	5.276%	$85.5368	$85.54	$85.55	$85.50
7 purchase totals =	$923.40		$1,005.9565	$1,005.96	$1,005.95	$1,006.10