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	$219.38	8.309%	$237.6083	$237.61	$237.60	$237.60
Purchase #2	$227.79	4.403%	$237.8196	$237.82	$237.80	$237.80
Purchase #3	$64.83	4.294%	$67.6138	$67.61	$67.60	$67.60
Purchase #4	$55.90	9.822%	$61.3905	$61.39	$61.40	$61.40
Purchase #5	$157.29	13.524%	$178.5619	$178.56	$178.55	$178.60
Purchase #6	$200.65	5.793%	$212.2737	$212.27	$212.25	$212.30
Purchase #7	$156.78	9.754%	$172.0723	$172.07	$172.05	$172.10
7 purchase totals =	$1,082.62		$1,167.3401	$1,167.33	$1,167.25	$1,167.40