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	$174.62	13.791%	$198.7018	$198.70	$198.70	$198.70
Purchase #2	$205.94	6.620%	$219.5732	$219.57	$219.55	$219.60
Purchase #3	$220.60	4.818%	$231.2285	$231.23	$231.25	$231.20
Purchase #4	$174.44	7.713%	$187.8946	$187.89	$187.90	$187.90
Purchase #5	$208.56	6.186%	$221.4615	$221.46	$221.45	$221.50
Purchase #6	$197.95	12.864%	$223.4143	$223.41	$223.40	$223.40
Purchase #7	$85.89	4.791%	$90.005	$90.01	$90.00	$90.00
7 purchase totals =	$1,268.00		$1,372.2789	$1,372.27	$1,372.25	$1,372.30