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	$49.83	10.787%	$55.2052	$55.21	$55.20	$55.20
Purchase #2	$82.54	11.840%	$92.3127	$92.31	$92.30	$92.30
Purchase #3	$46.77	13.548%	$53.1064	$53.11	$53.10	$53.10
Purchase #4	$195.80	6.450%	$208.4291	$208.43	$208.45	$208.40
Purchase #5	$248.94	6.744%	$265.7285	$265.73	$265.75	$265.70
Purchase #6	$197.87	12.647%	$222.8946	$222.89	$222.90	$222.90
Purchase #7	$109.27	6.730%	$116.6239	$116.62	$116.60	$116.60
7 purchase totals =	$931.02		$1,014.3004	$1,014.30	$1,014.30	$1,014.20