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	$116.69	7.522%	$125.4674	$125.47	$125.45	$125.50
Purchase #2	$32.89	7.132%	$35.2357	$35.24	$35.25	$35.20
Purchase #3	$116.26	3.543%	$120.3791	$120.38	$120.40	$120.40
Purchase #4	$112.80	13.171%	$127.6569	$127.66	$127.65	$127.70
Purchase #5	$171.76	4.592%	$179.6472	$179.65	$179.65	$179.60
Purchase #6	$68.53	5.188%	$72.0853	$72.09	$72.10	$72.10
Purchase #7	$74.77	12.271%	$83.945	$83.95	$83.95	$83.90
7 purchase totals =	$693.70		$744.4166	$744.44	$744.45	$744.40