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	$151.52	5.675%	$160.1188	$160.12	$160.10	$160.10
Purchase #2	$91.73	5.850%	$97.0962	$97.10	$97.10	$97.10
Purchase #3	$59.77	3.671%	$61.9642	$61.96	$61.95	$62.00
Purchase #4	$101.60	11.598%	$113.3836	$113.38	$113.40	$113.40
Purchase #5	$72.43	8.117%	$78.3091	$78.31	$78.30	$78.30
Purchase #6	$221.32	9.245%	$241.781	$241.78	$241.80	$241.80
Purchase #7	$192.40	10.545%	$212.6886	$212.69	$212.70	$212.70
7 purchase totals =	$890.77		$965.3415	$965.34	$965.35	$965.40