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	$187.68	11.212%	$208.7227	$208.72	$208.70	$208.70
Purchase #2	$152.31	7.243%	$163.3418	$163.34	$163.35	$163.30
Purchase #3	$99.37	3.814%	$103.16	$103.16	$103.15	$103.20
Purchase #4	$48.52	4.768%	$50.8334	$50.83	$50.85	$50.80
Purchase #5	$149.95	12.339%	$168.4523	$168.45	$168.45	$168.50
Purchase #6	$165.29	10.417%	$182.5083	$182.51	$182.50	$182.50
Purchase #7	$192.92	13.595%	$219.1475	$219.15	$219.15	$219.10
7 purchase totals =	$996.04		$1,096.1660	$1,096.16	$1,096.15	$1,096.10