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	$36.58	3.452%	$37.8427	$37.84	$37.85	$37.80
Purchase #2	$109.74	4.745%	$114.9472	$114.95	$114.95	$114.90
Purchase #3	$126.25	12.748%	$142.3444	$142.34	$142.35	$142.30
Purchase #4	$163.64	5.321%	$172.3473	$172.35	$172.35	$172.30
Purchase #5	$200.46	13.649%	$227.8208	$227.82	$227.80	$227.80
Purchase #6	$164.57	12.228%	$184.6936	$184.69	$184.70	$184.70
Purchase #7	$155.29	6.338%	$165.1323	$165.13	$165.15	$165.10
7 purchase totals =	$956.53		$1,045.1283	$1,045.12	$1,045.15	$1,044.90