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	$84.55	11.204%	$94.023	$94.02	$94.00	$94.00
Purchase #2	$215.81	11.247%	$240.0822	$240.08	$240.10	$240.10
Purchase #3	$203.80	4.755%	$213.4907	$213.49	$213.50	$213.50
Purchase #4	$123.46	11.569%	$137.7431	$137.74	$137.75	$137.70
Purchase #5	$189.76	9.857%	$208.4646	$208.46	$208.45	$208.50
Purchase #6	$149.38	7.690%	$160.8673	$160.87	$160.85	$160.90
Purchase #7	$55.86	6.712%	$59.6093	$59.61	$59.60	$59.60
7 purchase totals =	$1,022.62		$1,114.2802	$1,114.27	$1,114.25	$1,114.30