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	$119.25	5.539%	$125.8553	$125.86	$125.85	$125.90
Purchase #2	$42.32	4.311%	$44.1444	$44.14	$44.15	$44.10
Purchase #3	$76.74	3.622%	$79.5195	$79.52	$79.50	$79.50
Purchase #4	$73.31	12.663%	$82.5932	$82.59	$82.60	$82.60
Purchase #5	$37.58	10.338%	$41.465	$41.47	$41.45	$41.50
Purchase #6	$97.87	7.528%	$105.2377	$105.24	$105.25	$105.20
Purchase #7	$145.59	7.543%	$156.5719	$156.57	$156.55	$156.60
7 purchase totals =	$592.66		$635.3870	$635.39	$635.35	$635.40