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	$119.55	8.369%	$129.5551	$129.56	$129.55	$129.60
Purchase #2	$199.75	13.229%	$226.1749	$226.17	$226.15	$226.20
Purchase #3	$50.88	5.171%	$53.511	$53.51	$53.50	$53.50
Purchase #4	$200.28	7.487%	$215.275	$215.28	$215.30	$215.30
Purchase #5	$206.25	4.679%	$215.9004	$215.90	$215.90	$215.90
Purchase #6	$101.27	6.477%	$107.8293	$107.83	$107.85	$107.80
Purchase #7	$225.36	10.182%	$248.3062	$248.31	$248.30	$248.30
7 purchase totals =	$1,103.34		$1,196.5519	$1,196.56	$1,196.55	$1,196.60