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	$176.42	5.801%	$186.6541	$186.65	$186.65	$186.70
Purchase #2	$111.91	10.721%	$123.9079	$123.91	$123.90	$123.90
Purchase #3	$123.80	11.341%	$137.8402	$137.84	$137.85	$137.80
Purchase #4	$220.38	3.668%	$228.4635	$228.46	$228.45	$228.50
Purchase #5	$43.39	5.773%	$45.8949	$45.89	$45.90	$45.90
Purchase #6	$159.55	3.464%	$165.0768	$165.08	$165.10	$165.10
Purchase #7	$206.53	7.552%	$222.1271	$222.13	$222.15	$222.10
7 purchase totals =	$1,041.98		$1,109.9645	$1,109.96	$1,110.00	$1,110.00