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	$99.64	9.398%	$109.0042	$109.00	$109.00	$109.00
Purchase #2	$146.67	3.718%	$152.1232	$152.12	$152.10	$152.10
Purchase #3	$112.25	10.165%	$123.6602	$123.66	$123.65	$123.70
Purchase #4	$175.48	13.110%	$198.4854	$198.49	$198.50	$198.50
Purchase #5	$107.82	3.132%	$111.1969	$111.20	$111.20	$111.20
Purchase #6	$133.33	4.483%	$139.3072	$139.31	$139.30	$139.30
Purchase #7	$169.37	12.831%	$191.1019	$191.10	$191.10	$191.10
7 purchase totals =	$944.56		$1,024.8790	$1,024.88	$1,024.85	$1,024.90