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	$176.39	11.371%	$196.4473	$196.45	$196.45	$196.40
Purchase #2	$199.71	4.604%	$208.9046	$208.90	$208.90	$208.90
Purchase #3	$213.57	5.170%	$224.6116	$224.61	$224.60	$224.60
Purchase #4	$28.90	9.199%	$31.5585	$31.56	$31.55	$31.60
Purchase #5	$234.39	6.345%	$249.262	$249.26	$249.25	$249.30
Purchase #6	$54.45	9.140%	$59.4267	$59.43	$59.45	$59.40
Purchase #7	$183.31	6.592%	$195.3938	$195.39	$195.40	$195.40
7 purchase totals =	$1,090.72		$1,165.6045	$1,165.60	$1,165.60	$1,165.60