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	$151.68	4.383%	$158.3281	$158.33	$158.35	$158.30
Purchase #2	$134.95	4.600%	$141.1577	$141.16	$141.15	$141.20
Purchase #3	$68.97	7.162%	$73.9096	$73.91	$73.90	$73.90
Purchase #4	$90.63	10.868%	$100.4797	$100.48	$100.50	$100.50
Purchase #5	$181.80	3.434%	$188.043	$188.04	$188.05	$188.00
Purchase #6	$13.56	4.250%	$14.1363	$14.14	$14.15	$14.10
Purchase #7	$121.55	5.266%	$127.9508	$127.95	$127.95	$128.00
7 purchase totals =	$763.14		$804.0052	$804.01	$804.05	$804.00