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	$167.61	12.335%	$188.2847	$188.28	$188.30	$188.30
Purchase #2	$82.96	3.186%	$85.6031	$85.60	$85.60	$85.60
Purchase #3	$6.86	13.383%	$7.7781	$7.78	$7.80	$7.80
Purchase #4	$157.96	13.397%	$179.1219	$179.12	$179.10	$179.10
Purchase #5	$238.34	7.455%	$256.1082	$256.11	$256.10	$256.10
Purchase #6	$190.63	6.491%	$203.0038	$203.00	$203.00	$203.00
Purchase #7	$153.64	13.288%	$174.0557	$174.06	$174.05	$174.10
7 purchase totals =	$998.00		$1,093.9555	$1,093.95	$1,093.95	$1,094.00