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	$92.51	3.625%	$95.8635	$95.86	$95.85	$95.90
Purchase #2	$107.32	9.116%	$117.1033	$117.10	$117.10	$117.10
Purchase #3	$151.64	12.809%	$171.0636	$171.06	$171.05	$171.10
Purchase #4	$57.96	13.183%	$65.6009	$65.60	$65.60	$65.60
Purchase #5	$157.72	6.239%	$167.5602	$167.56	$167.55	$167.60
Purchase #6	$221.72	9.469%	$242.7147	$242.71	$242.70	$242.70
Purchase #7	$231.78	8.383%	$251.2101	$251.21	$251.20	$251.20
7 purchase totals =	$1,020.65		$1,111.1163	$1,111.10	$1,111.05	$1,111.20