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	$235.74	10.439%	$260.3489	$260.35	$260.35	$260.30
Purchase #2	$57.40	13.167%	$64.9579	$64.96	$64.95	$65.00
Purchase #3	$162.60	12.298%	$182.5965	$182.60	$182.60	$182.60
Purchase #4	$176.70	11.192%	$196.4763	$196.48	$196.50	$196.50
Purchase #5	$68.96	13.553%	$78.3061	$78.31	$78.30	$78.30
Purchase #6	$244.34	11.350%	$272.0726	$272.07	$272.05	$272.10
Purchase #7	$54.28	5.487%	$57.2583	$57.26	$57.25	$57.30
7 purchase totals =	$1,000.02		$1,112.0166	$1,112.03	$1,112.00	$1,112.10