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	$244.31	7.225%	$261.9614	$261.96	$261.95	$262.00
Purchase #2	$7.55	11.444%	$8.414	$8.41	$8.40	$8.40
Purchase #3	$79.77	13.712%	$90.7081	$90.71	$90.70	$90.70
Purchase #4	$119.47	5.417%	$125.9417	$125.94	$125.95	$125.90
Purchase #5	$48.95	10.761%	$54.2175	$54.22	$54.20	$54.20
Purchase #6	$179.71	9.572%	$196.9118	$196.91	$196.90	$196.90
Purchase #7	$202.40	7.419%	$217.4161	$217.42	$217.40	$217.40
7 purchase totals =	$882.16		$955.5706	$955.57	$955.50	$955.50