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	$45.49	3.171%	$46.9325	$46.93	$46.95	$46.90
Purchase #2	$107.41	4.720%	$112.4798	$112.48	$112.50	$112.50
Purchase #3	$131.88	11.498%	$147.0436	$147.04	$147.05	$147.00
Purchase #4	$38.60	5.254%	$40.628	$40.63	$40.65	$40.60
Purchase #5	$161.55	6.728%	$172.4191	$172.42	$172.40	$172.40
Purchase #6	$75.68	9.500%	$82.8696	$82.87	$82.85	$82.90
Purchase #7	$140.40	11.754%	$156.9026	$156.90	$156.90	$156.90
7 purchase totals =	$701.01		$759.2752	$759.27	$759.30	$759.20