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	$199.47	4.405%	$208.2567	$208.26	$208.25	$208.30
Purchase #2	$122.43	11.573%	$136.5988	$136.60	$136.60	$136.60
Purchase #3	$18.62	11.384%	$20.7397	$20.74	$20.75	$20.70
Purchase #4	$135.30	11.523%	$150.8906	$150.89	$150.90	$150.90
Purchase #5	$192.86	12.253%	$216.4911	$216.49	$216.50	$216.50
Purchase #6	$236.95	12.578%	$266.7536	$266.75	$266.75	$266.80
Purchase #7	$54.78	11.571%	$61.1186	$61.12	$61.10	$61.10
7 purchase totals =	$960.41		$1,060.8491	$1,060.85	$1,060.85	$1,060.90