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	$190.77	4.501%	$199.3566	$199.36	$199.35	$199.40
Purchase #2	$242.27	4.569%	$253.3393	$253.34	$253.35	$253.30
Purchase #3	$164.94	4.656%	$172.6196	$172.62	$172.60	$172.60
Purchase #4	$98.33	11.759%	$109.8926	$109.89	$109.90	$109.90
Purchase #5	$124.34	6.175%	$132.018	$132.02	$132.00	$132.00
Purchase #6	$40.86	10.631%	$45.2038	$45.20	$45.20	$45.20
Purchase #7	$214.63	6.555%	$228.699	$228.70	$228.70	$228.70
7 purchase totals =	$1,076.14		$1,141.1289	$1,141.13	$1,141.10	$1,141.10