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	$211.38	10.576%	$233.7355	$233.74	$233.75	$233.70
Purchase #2	$116.81	8.873%	$127.1746	$127.17	$127.15	$127.20
Purchase #3	$155.59	7.440%	$167.1659	$167.17	$167.15	$167.20
Purchase #4	$101.46	10.150%	$111.7582	$111.76	$111.75	$111.80
Purchase #5	$217.37	5.448%	$229.2123	$229.21	$229.20	$229.20
Purchase #6	$64.39	3.447%	$66.6095	$66.61	$66.60	$66.60
Purchase #7	$224.33	9.861%	$246.4512	$246.45	$246.45	$246.50
7 purchase totals =	$1,091.33		$1,182.1072	$1,182.11	$1,182.05	$1,182.20