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	$109.27	5.108%	$114.8515	$114.85	$114.85	$114.90
Purchase #2	$161.59	3.326%	$166.9645	$166.96	$166.95	$167.00
Purchase #3	$31.43	9.428%	$34.3932	$34.39	$34.40	$34.40
Purchase #4	$145.42	8.818%	$158.2431	$158.24	$158.25	$158.20
Purchase #5	$142.54	13.252%	$161.4294	$161.43	$161.45	$161.40
Purchase #6	$170.25	9.136%	$185.804	$185.80	$185.80	$185.80
Purchase #7	$175.32	3.102%	$180.7584	$180.76	$180.75	$180.80
7 purchase totals =	$935.82		$1,002.4441	$1,002.43	$1,002.45	$1,002.50