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	$119.63	10.287%	$131.9363	$131.94	$131.95	$131.90
Purchase #2	$92.27	10.870%	$102.2997	$102.30	$102.30	$102.30
Purchase #3	$165.43	4.437%	$172.7701	$172.77	$172.75	$172.80
Purchase #4	$201.63	8.118%	$217.9983	$218.00	$218.00	$218.00
Purchase #5	$41.50	9.615%	$45.4902	$45.49	$45.50	$45.50
Purchase #6	$151.71	6.152%	$161.0432	$161.04	$161.05	$161.00
Purchase #7	$96.66	13.419%	$109.6308	$109.63	$109.65	$109.60
7 purchase totals =	$868.83		$941.1686	$941.17	$941.20	$941.10