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	$212.68	13.391%	$241.16	$241.16	$241.15	$241.20
Purchase #2	$78.43	13.658%	$89.142	$89.14	$89.15	$89.10
Purchase #3	$162.70	13.400%	$184.5018	$184.50	$184.50	$184.50
Purchase #4	$146.89	13.658%	$166.9522	$166.95	$166.95	$167.00
Purchase #5	$151.86	7.299%	$162.9443	$162.94	$162.95	$162.90
Purchase #6	$100.82	9.292%	$110.1882	$110.19	$110.20	$110.20
Purchase #7	$35.92	4.537%	$37.5497	$37.55	$37.55	$37.50
7 purchase totals =	$889.30		$992.4382	$992.43	$992.45	$992.40