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	$41.44	7.691%	$44.6272	$44.63	$44.65	$44.60
Purchase #2	$185.90	12.853%	$209.7937	$209.79	$209.80	$209.80
Purchase #3	$78.93	10.618%	$87.3108	$87.31	$87.30	$87.30
Purchase #4	$112.41	9.827%	$123.4565	$123.46	$123.45	$123.50
Purchase #5	$158.44	4.743%	$165.9548	$165.95	$165.95	$166.00
Purchase #6	$156.77	5.269%	$165.0302	$165.03	$165.05	$165.00
Purchase #7	$34.80	7.664%	$37.4671	$37.47	$37.45	$37.50
7 purchase totals =	$768.69		$833.6403	$833.64	$833.65	$833.70