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	$111.61	10.805%	$123.6695	$123.67	$123.65	$123.70
Purchase #2	$232.34	3.506%	$240.4858	$240.49	$240.50	$240.50
Purchase #3	$153.54	13.763%	$174.6717	$174.67	$174.65	$174.70
Purchase #4	$13.52	10.449%	$14.9327	$14.93	$14.95	$14.90
Purchase #5	$234.52	13.241%	$265.5728	$265.57	$265.55	$265.60
Purchase #6	$110.49	11.641%	$123.3521	$123.35	$123.35	$123.40
Purchase #7	$229.80	5.455%	$242.3356	$242.34	$242.35	$242.30
7 purchase totals =	$1,085.82		$1,185.0202	$1,185.02	$1,185.00	$1,185.10