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	$113.75	10.220%	$125.3753	$125.38	$125.40	$125.40
Purchase #2	$149.56	11.762%	$167.1512	$167.15	$167.15	$167.20
Purchase #3	$69.76	9.852%	$76.6328	$76.63	$76.65	$76.60
Purchase #4	$160.78	4.781%	$168.4669	$168.47	$168.45	$168.50
Purchase #5	$86.43	3.317%	$89.2969	$89.30	$89.30	$89.30
Purchase #6	$194.94	7.495%	$209.5508	$209.55	$209.55	$209.60
Purchase #7	$112.84	13.220%	$127.7574	$127.76	$127.75	$127.80
7 purchase totals =	$888.06		$964.2313	$964.24	$964.25	$964.40