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	$10.76	7.545%	$11.5718	$11.57	$11.55	$11.60
Purchase #2	$31.57	3.776%	$32.7621	$32.76	$32.75	$32.80
Purchase #3	$43.56	11.489%	$48.5646	$48.56	$48.55	$48.60
Purchase #4	$245.40	8.456%	$266.151	$266.15	$266.15	$266.20
Purchase #5	$245.81	5.570%	$259.5016	$259.50	$259.50	$259.50
Purchase #6	$243.42	12.700%	$274.3343	$274.33	$274.35	$274.30
Purchase #7	$197.64	5.387%	$208.2869	$208.29	$208.30	$208.30
7 purchase totals =	$1,018.16		$1,101.1723	$1,101.16	$1,101.15	$1,101.30