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	$131.86	10.736%	$146.0165	$146.02	$146.00	$146.00
Purchase #2	$104.84	4.812%	$109.8849	$109.88	$109.90	$109.90
Purchase #3	$234.98	5.569%	$248.066	$248.07	$248.05	$248.10
Purchase #4	$39.72	4.522%	$41.5161	$41.52	$41.50	$41.50
Purchase #5	$245.38	4.654%	$256.8	$256.80	$256.80	$256.80
Purchase #6	$134.96	3.862%	$140.1722	$140.17	$140.15	$140.20
Purchase #7	$250.49	9.290%	$273.7605	$273.76	$273.75	$273.80
7 purchase totals =	$1,142.23		$1,216.2162	$1,216.22	$1,216.15	$1,216.30