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	$234.33	12.429%	$263.4549	$263.45	$263.45	$263.50
Purchase #2	$10.62	7.867%	$11.4555	$11.46	$11.45	$11.50
Purchase #3	$42.38	5.677%	$44.7859	$44.79	$44.80	$44.80
Purchase #4	$162.72	10.320%	$179.5127	$179.51	$179.50	$179.50
Purchase #5	$63.78	6.227%	$67.7516	$67.75	$67.75	$67.80
Purchase #6	$250.43	6.327%	$266.2747	$266.27	$266.25	$266.30
Purchase #7	$202.49	6.245%	$215.1355	$215.14	$215.15	$215.10
7 purchase totals =	$966.75		$1,048.3708	$1,048.37	$1,048.35	$1,048.50