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	$149.98	7.438%	$161.1355	$161.14	$161.15	$161.10
Purchase #2	$171.55	10.245%	$189.1253	$189.13	$189.15	$189.10
Purchase #3	$78.94	13.325%	$89.4588	$89.46	$89.45	$89.50
Purchase #4	$230.60	5.649%	$243.6266	$243.63	$243.65	$243.60
Purchase #5	$82.81	4.177%	$86.269	$86.27	$86.25	$86.30
Purchase #6	$130.99	12.493%	$147.3546	$147.35	$147.35	$147.40
Purchase #7	$207.89	9.328%	$227.282	$227.28	$227.30	$227.30
7 purchase totals =	$1,052.76		$1,144.2518	$1,144.26	$1,144.30	$1,144.30