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	$119.37	4.348%	$124.5602	$124.56	$124.55	$124.60
Purchase #2	$148.76	10.814%	$164.8469	$164.85	$164.85	$164.80
Purchase #3	$18.44	9.771%	$20.2418	$20.24	$20.25	$20.20
Purchase #4	$153.25	7.247%	$164.356	$164.36	$164.35	$164.40
Purchase #5	$232.95	13.537%	$264.4844	$264.48	$264.50	$264.50
Purchase #6	$107.42	8.494%	$116.5443	$116.54	$116.55	$116.50
Purchase #7	$198.55	3.310%	$205.122	$205.12	$205.10	$205.10
7 purchase totals =	$978.74		$1,060.1556	$1,060.15	$1,060.15	$1,060.10