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	$156.52	3.800%	$162.4678	$162.47	$162.45	$162.50
Purchase #2	$71.82	12.576%	$80.8521	$80.85	$80.85	$80.90
Purchase #3	$161.74	3.682%	$167.6953	$167.70	$167.70	$167.70
Purchase #4	$50.87	4.673%	$53.2472	$53.25	$53.25	$53.20
Purchase #5	$211.90	13.270%	$240.0191	$240.02	$240.00	$240.00
Purchase #6	$217.79	7.585%	$234.3094	$234.31	$234.30	$234.30
Purchase #7	$154.60	11.514%	$172.4006	$172.40	$172.40	$172.40
7 purchase totals =	$1,025.24		$1,110.9915	$1,111.00	$1,110.95	$1,111.00