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	$196.59	4.353%	$205.1476	$205.15	$205.15	$205.10
Purchase #2	$59.66	5.497%	$62.9395	$62.94	$62.95	$62.90
Purchase #3	$122.95	10.860%	$136.3024	$136.30	$136.30	$136.30
Purchase #4	$151.53	8.852%	$164.9434	$164.94	$164.95	$164.90
Purchase #5	$166.35	3.138%	$171.5701	$171.57	$171.55	$171.60
Purchase #6	$230.41	5.652%	$243.4328	$243.43	$243.45	$243.40
Purchase #7	$145.63	9.802%	$159.9047	$159.90	$159.90	$159.90
7 purchase totals =	$1,073.12		$1,144.2405	$1,144.23	$1,144.25	$1,144.10