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	$246.93	6.448%	$262.852	$262.85	$262.85	$262.90
Purchase #2	$140.94	9.180%	$153.8783	$153.88	$153.90	$153.90
Purchase #3	$40.26	4.639%	$42.1277	$42.13	$42.15	$42.10
Purchase #4	$147.27	3.288%	$152.1122	$152.11	$152.10	$152.10
Purchase #5	$182.92	5.133%	$192.3093	$192.31	$192.30	$192.30
Purchase #6	$59.79	5.242%	$62.9242	$62.92	$62.90	$62.90
Purchase #7	$216.97	13.147%	$245.495	$245.50	$245.50	$245.50
7 purchase totals =	$1,035.08		$1,111.6987	$1,111.70	$1,111.70	$1,111.70