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	$201.71	7.471%	$216.7798	$216.78	$216.80	$216.80
Purchase #2	$200.45	9.694%	$219.8816	$219.88	$219.90	$219.90
Purchase #3	$69.88	3.653%	$72.4327	$72.43	$72.45	$72.40
Purchase #4	$13.85	5.705%	$14.6401	$14.64	$14.65	$14.60
Purchase #5	$133.41	13.284%	$151.1322	$151.13	$151.15	$151.10
Purchase #6	$178.94	8.219%	$193.6471	$193.65	$193.65	$193.60
Purchase #7	$177.82	5.111%	$186.9084	$186.91	$186.90	$186.90
7 purchase totals =	$976.06		$1,055.4219	$1,055.42	$1,055.50	$1,055.30