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	$84.88	3.215%	$87.6089	$87.61	$87.60	$87.60
Purchase #2	$242.67	10.698%	$268.6308	$268.63	$268.65	$268.60
Purchase #3	$64.47	12.535%	$72.5513	$72.55	$72.55	$72.60
Purchase #4	$66.40	8.441%	$72.0048	$72.00	$72.00	$72.00
Purchase #5	$98.77	3.292%	$102.0215	$102.02	$102.00	$102.00
Purchase #6	$195.99	11.517%	$218.5622	$218.56	$218.55	$218.60
Purchase #7	$172.94	9.601%	$189.544	$189.54	$189.55	$189.50
7 purchase totals =	$926.12		$1,010.9235	$1,010.91	$1,010.90	$1,010.90