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	$177.86	10.733%	$196.9497	$196.95	$196.95	$196.90
Purchase #2	$245.57	8.844%	$267.2882	$267.29	$267.30	$267.30
Purchase #3	$82.29	4.464%	$85.9634	$85.96	$85.95	$86.00
Purchase #4	$118.53	8.605%	$128.7295	$128.73	$128.75	$128.70
Purchase #5	$85.56	10.262%	$94.3402	$94.34	$94.35	$94.30
Purchase #6	$78.95	8.842%	$85.9308	$85.93	$85.95	$85.90
Purchase #7	$138.33	6.521%	$147.3505	$147.35	$147.35	$147.40
7 purchase totals =	$927.09		$1,006.5523	$1,006.55	$1,006.60	$1,006.50