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	$212.40	10.574%	$234.8592	$234.86	$234.85	$234.90
Purchase #2	$14.89	13.311%	$16.872	$16.87	$16.85	$16.90
Purchase #3	$247.29	6.560%	$263.5122	$263.51	$263.50	$263.50
Purchase #4	$28.82	10.507%	$31.8481	$31.85	$31.85	$31.80
Purchase #5	$82.57	5.534%	$87.1394	$87.14	$87.15	$87.10
Purchase #6	$148.64	3.813%	$154.3076	$154.31	$154.30	$154.30
Purchase #7	$250.86	10.774%	$277.8877	$277.89	$277.90	$277.90
7 purchase totals =	$985.47		$1,066.4262	$1,066.43	$1,066.40	$1,066.40