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	$232.32	7.764%	$250.3573	$250.36	$250.35	$250.40
Purchase #2	$32.95	13.364%	$37.3534	$37.35	$37.35	$37.40
Purchase #3	$12.35	12.566%	$13.9019	$13.90	$13.90	$13.90
Purchase #4	$23.82	5.296%	$25.0815	$25.08	$25.10	$25.10
Purchase #5	$217.46	10.326%	$239.9149	$239.91	$239.90	$239.90
Purchase #6	$205.55	3.380%	$212.4976	$212.50	$212.50	$212.50
Purchase #7	$222.33	6.604%	$237.0127	$237.01	$237.00	$237.00
7 purchase totals =	$946.78		$1,016.1193	$1,016.11	$1,016.10	$1,016.20