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	$48.33	13.517%	$54.8628	$54.86	$54.85	$54.90
Purchase #2	$87.49	12.454%	$98.386	$98.39	$98.40	$98.40
Purchase #3	$169.35	7.684%	$182.3629	$182.36	$182.35	$182.40
Purchase #4	$170.96	3.156%	$176.3555	$176.36	$176.35	$176.40
Purchase #5	$185.65	5.873%	$196.5532	$196.55	$196.55	$196.60
Purchase #6	$164.92	5.593%	$174.144	$174.14	$174.15	$174.10
Purchase #7	$227.55	3.530%	$235.5825	$235.58	$235.60	$235.60
7 purchase totals =	$1,054.25		$1,118.2469	$1,118.24	$1,118.25	$1,118.40