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	$104.91	7.674%	$112.9608	$112.96	$112.95	$113.00
Purchase #2	$55.46	6.789%	$59.2252	$59.23	$59.25	$59.20
Purchase #3	$75.72	9.524%	$82.9316	$82.93	$82.95	$82.90
Purchase #4	$84.71	10.142%	$93.3013	$93.30	$93.30	$93.30
Purchase #5	$94.45	11.221%	$105.0482	$105.05	$105.05	$105.00
Purchase #6	$35.79	3.733%	$37.126	$37.13	$37.15	$37.10
Purchase #7	$129.76	3.271%	$134.0044	$134.00	$134.00	$134.00
7 purchase totals =	$580.80		$624.5975	$624.60	$624.65	$624.50