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	$181.96	5.261%	$191.5329	$191.53	$191.55	$191.50
Purchase #2	$176.40	4.614%	$184.5391	$184.54	$184.55	$184.50
Purchase #3	$202.38	4.556%	$211.6004	$211.60	$211.60	$211.60
Purchase #4	$168.62	4.846%	$176.7913	$176.79	$176.80	$176.80
Purchase #5	$46.39	4.800%	$48.6167	$48.62	$48.60	$48.60
Purchase #6	$143.38	3.277%	$148.0786	$148.08	$148.10	$148.10
Purchase #7	$175.90	7.531%	$189.147	$189.15	$189.15	$189.10
7 purchase totals =	$1,095.03		$1,150.3060	$1,150.31	$1,150.35	$1,150.20