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	$38.82	11.186%	$43.1624	$43.16	$43.15	$43.20
Purchase #2	$83.69	11.549%	$93.3554	$93.36	$93.35	$93.40
Purchase #3	$170.69	5.387%	$179.8851	$179.89	$179.90	$179.90
Purchase #4	$76.80	4.731%	$80.4334	$80.43	$80.45	$80.40
Purchase #5	$226.64	8.810%	$246.607	$246.61	$246.60	$246.60
Purchase #6	$156.45	5.316%	$164.7669	$164.77	$164.75	$164.80
Purchase #7	$197.28	8.420%	$213.891	$213.89	$213.90	$213.90
7 purchase totals =	$950.37		$1,022.1012	$1,022.11	$1,022.10	$1,022.20