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	$212.25	7.150%	$227.4259	$227.43	$227.45	$227.40
Purchase #2	$106.90	10.452%	$118.0732	$118.07	$118.05	$118.10
Purchase #3	$137.78	3.107%	$142.0608	$142.06	$142.05	$142.10
Purchase #4	$103.41	6.244%	$109.8669	$109.87	$109.85	$109.90
Purchase #5	$169.44	9.834%	$186.1027	$186.10	$186.10	$186.10
Purchase #6	$159.70	7.546%	$171.751	$171.75	$171.75	$171.80
Purchase #7	$227.84	12.623%	$256.6002	$256.60	$256.60	$256.60
7 purchase totals =	$1,117.32		$1,211.8807	$1,211.88	$1,211.85	$1,212.00