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	$119.25	5.436%	$125.7324	$125.73	$125.75	$125.70
Purchase #2	$175.70	3.292%	$181.484	$181.48	$181.50	$181.50
Purchase #3	$95.33	9.820%	$104.6914	$104.69	$104.70	$104.70
Purchase #4	$191.91	3.269%	$198.1835	$198.18	$198.20	$198.20
Purchase #5	$151.47	8.435%	$164.2465	$164.25	$164.25	$164.20
Purchase #6	$177.35	10.860%	$196.6102	$196.61	$196.60	$196.60
Purchase #7	$7.30	8.510%	$7.9212	$7.92	$7.90	$7.90
7 purchase totals =	$918.31		$978.8692	$978.86	$978.90	$978.80