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	$113.69	8.269%	$123.091	$123.09	$123.10	$123.10
Purchase #2	$105.60	11.358%	$117.594	$117.59	$117.60	$117.60
Purchase #3	$81.73	6.399%	$86.9599	$86.96	$86.95	$87.00
Purchase #4	$152.45	8.175%	$164.9128	$164.91	$164.90	$164.90
Purchase #5	$197.84	12.788%	$223.1398	$223.14	$223.15	$223.10
Purchase #6	$183.40	9.309%	$200.4727	$200.47	$200.45	$200.50
Purchase #7	$86.88	9.537%	$95.1657	$95.17	$95.15	$95.20
7 purchase totals =	$921.59		$1,011.3359	$1,011.33	$1,011.30	$1,011.40