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	$168.40	10.845%	$186.663	$186.66	$186.65	$186.70
Purchase #2	$96.91	13.103%	$109.6081	$109.61	$109.60	$109.60
Purchase #3	$36.46	3.732%	$37.8207	$37.82	$37.80	$37.80
Purchase #4	$241.53	7.672%	$260.0602	$260.06	$260.05	$260.10
Purchase #5	$61.62	3.617%	$63.8488	$63.85	$63.85	$63.80
Purchase #6	$248.80	10.822%	$275.7251	$275.73	$275.75	$275.70
Purchase #7	$156.81	13.684%	$178.2679	$178.27	$178.25	$178.30
7 purchase totals =	$1,010.53		$1,111.9938	$1,112.00	$1,111.95	$1,112.00