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	$146.40	5.489%	$154.4359	$154.44	$154.45	$154.40
Purchase #2	$9.61	10.577%	$10.6264	$10.63	$10.65	$10.60
Purchase #3	$64.82	8.621%	$70.4081	$70.41	$70.40	$70.40
Purchase #4	$95.74	3.415%	$99.0095	$99.01	$99.00	$99.00
Purchase #5	$244.55	10.759%	$270.8611	$270.86	$270.85	$270.90
Purchase #6	$246.39	5.493%	$259.9242	$259.92	$259.90	$259.90
Purchase #7	$70.54	10.656%	$78.0567	$78.06	$78.05	$78.10
7 purchase totals =	$878.05		$943.3219	$943.33	$943.30	$943.30