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	$169.52	11.687%	$189.3318	$189.33	$189.35	$189.30
Purchase #2	$9.90	11.852%	$11.0733	$11.07	$11.05	$11.10
Purchase #3	$136.32	12.217%	$152.9742	$152.97	$152.95	$153.00
Purchase #4	$80.55	5.665%	$85.1132	$85.11	$85.10	$85.10
Purchase #5	$227.43	12.808%	$256.5592	$256.56	$256.55	$256.60
Purchase #6	$187.72	3.336%	$193.9823	$193.98	$194.00	$194.00
Purchase #7	$53.58	10.812%	$59.3731	$59.37	$59.35	$59.40
7 purchase totals =	$865.02		$948.4071	$948.39	$948.35	$948.50