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	$155.84	4.290%	$162.5255	$162.53	$162.55	$162.50
Purchase #2	$29.89	3.145%	$30.83	$30.83	$30.85	$30.80
Purchase #3	$70.95	8.730%	$77.1439	$77.14	$77.15	$77.10
Purchase #4	$47.88	6.782%	$51.1272	$51.13	$51.15	$51.10
Purchase #5	$55.42	7.510%	$59.582	$59.58	$59.60	$59.60
Purchase #6	$145.78	4.529%	$152.3824	$152.38	$152.40	$152.40
Purchase #7	$158.83	4.663%	$166.2362	$166.24	$166.25	$166.20
7 purchase totals =	$664.59		$699.8272	$699.83	$699.95	$699.70