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	$114.31	11.518%	$127.4762	$127.48	$127.50	$127.50
Purchase #2	$88.51	13.461%	$100.4243	$100.42	$100.40	$100.40
Purchase #3	$30.61	11.279%	$34.0625	$34.06	$34.05	$34.10
Purchase #4	$216.84	11.845%	$242.5247	$242.52	$242.50	$242.50
Purchase #5	$219.63	13.300%	$248.8408	$248.84	$248.85	$248.80
Purchase #6	$70.48	9.189%	$76.9564	$76.96	$76.95	$77.00
Purchase #7	$179.91	7.864%	$194.0581	$194.06	$194.05	$194.10
7 purchase totals =	$920.29		$1,024.3430	$1,024.34	$1,024.30	$1,024.40