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	$177.54	7.234%	$190.3832	$190.38	$190.40	$190.40
Purchase #2	$80.68	5.799%	$85.3586	$85.36	$85.35	$85.40
Purchase #3	$33.35	13.421%	$37.8259	$37.83	$37.85	$37.80
Purchase #4	$207.45	13.236%	$234.9081	$234.91	$234.90	$234.90
Purchase #5	$78.67	6.254%	$83.59	$83.59	$83.60	$83.60
Purchase #6	$133.37	5.720%	$140.9988	$141.00	$141.00	$141.00
Purchase #7	$215.89	11.783%	$241.3283	$241.33	$241.35	$241.30
7 purchase totals =	$926.95		$1,014.3929	$1,014.40	$1,014.45	$1,014.40