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	$216.73	5.493%	$228.635	$228.64	$228.65	$228.60
Purchase #2	$212.31	5.811%	$224.6473	$224.65	$224.65	$224.60
Purchase #3	$38.42	7.604%	$41.3415	$41.34	$41.35	$41.30
Purchase #4	$45.90	7.789%	$49.4752	$49.48	$49.50	$49.50
Purchase #5	$118.97	7.511%	$127.9058	$127.91	$127.90	$127.90
Purchase #6	$75.85	8.409%	$82.2282	$82.23	$82.25	$82.20
Purchase #7	$214.54	3.376%	$221.7829	$221.78	$221.80	$221.80
7 purchase totals =	$922.72		$976.0159	$976.03	$976.10	$975.90