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	$224.47	4.614%	$234.827	$234.83	$234.85	$234.80
Purchase #2	$169.25	13.704%	$192.444	$192.44	$192.45	$192.40
Purchase #3	$231.69	4.686%	$242.547	$242.55	$242.55	$242.50
Purchase #4	$85.40	7.624%	$91.9109	$91.91	$91.90	$91.90
Purchase #5	$210.43	5.453%	$221.9047	$221.90	$221.90	$221.90
Purchase #6	$112.92	6.469%	$120.2248	$120.22	$120.20	$120.20
Purchase #7	$6.75	13.656%	$7.6718	$7.67	$7.65	$7.70
7 purchase totals =	$1,040.91		$1,111.5302	$1,111.52	$1,111.50	$1,111.40