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	$94.50	11.459%	$105.3288	$105.33	$105.35	$105.30
Purchase #2	$10.26	7.314%	$11.0104	$11.01	$11.00	$11.00
Purchase #3	$129.45	13.799%	$147.3128	$147.31	$147.30	$147.30
Purchase #4	$132.45	13.537%	$150.3798	$150.38	$150.40	$150.40
Purchase #5	$81.88	13.228%	$92.7111	$92.71	$92.70	$92.70
Purchase #6	$170.72	13.622%	$193.9755	$193.98	$194.00	$194.00
Purchase #7	$117.83	8.400%	$127.7277	$127.73	$127.75	$127.70
7 purchase totals =	$737.09		$828.4461	$828.45	$828.50	$828.40