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	$164.90	13.617%	$187.3544	$187.35	$187.35	$187.40
Purchase #2	$17.89	3.648%	$18.5426	$18.54	$18.55	$18.50
Purchase #3	$26.46	10.247%	$29.1714	$29.17	$29.15	$29.20
Purchase #4	$73.58	13.850%	$83.7708	$83.77	$83.75	$83.80
Purchase #5	$115.93	13.784%	$131.9098	$131.91	$131.90	$131.90
Purchase #6	$83.74	10.180%	$92.2647	$92.26	$92.25	$92.30
Purchase #7	$140.47	13.580%	$159.5458	$159.55	$159.55	$159.50
7 purchase totals =	$622.97		$702.5595	$702.55	$702.50	$702.60