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	$158.50	5.168%	$166.6913	$166.69	$166.70	$166.70
Purchase #2	$19.77	3.454%	$20.4529	$20.45	$20.45	$20.50
Purchase #3	$172.29	4.824%	$180.6013	$180.60	$180.60	$180.60
Purchase #4	$181.37	11.684%	$202.5613	$202.56	$202.55	$202.60
Purchase #5	$201.61	9.424%	$220.6097	$220.61	$220.60	$220.60
Purchase #6	$186.95	5.176%	$196.6265	$196.63	$196.65	$196.60
Purchase #7	$111.50	4.525%	$116.5454	$116.55	$116.55	$116.50
7 purchase totals =	$1,031.99		$1,104.0884	$1,104.09	$1,104.10	$1,104.10