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	$182.64	6.528%	$194.5627	$194.56	$194.55	$194.60
Purchase #2	$127.52	4.763%	$133.5938	$133.59	$133.60	$133.60
Purchase #3	$133.87	7.521%	$143.9384	$143.94	$143.95	$143.90
Purchase #4	$79.87	3.430%	$82.6095	$82.61	$82.60	$82.60
Purchase #5	$38.35	6.603%	$40.8823	$40.88	$40.90	$40.90
Purchase #6	$177.78	6.197%	$188.797	$188.80	$188.80	$188.80
Purchase #7	$155.76	5.299%	$164.0137	$164.01	$164.00	$164.00
7 purchase totals =	$895.79		$948.3974	$948.39	$948.40	$948.40