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	$210.35	7.167%	$225.4258	$225.43	$225.45	$225.40
Purchase #2	$47.84	12.472%	$53.8066	$53.81	$53.80	$53.80
Purchase #3	$147.38	6.655%	$157.1881	$157.19	$157.20	$157.20
Purchase #4	$168.70	3.521%	$174.6399	$174.64	$174.65	$174.60
Purchase #5	$153.59	3.635%	$159.173	$159.17	$159.15	$159.20
Purchase #6	$189.70	5.225%	$199.6118	$199.61	$199.60	$199.60
Purchase #7	$166.54	3.533%	$172.4239	$172.42	$172.40	$172.40
7 purchase totals =	$1,084.10		$1,142.2691	$1,142.27	$1,142.25	$1,142.20