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	$80.81	9.572%	$88.5451	$88.55	$88.55	$88.50
Purchase #2	$105.42	6.216%	$111.9729	$111.97	$111.95	$112.00
Purchase #3	$31.40	3.287%	$32.4321	$32.43	$32.45	$32.40
Purchase #4	$173.30	4.761%	$181.5508	$181.55	$181.55	$181.60
Purchase #5	$123.96	3.457%	$128.2453	$128.25	$128.25	$128.20
Purchase #6	$237.75	13.743%	$270.424	$270.42	$270.40	$270.40
Purchase #7	$215.58	10.109%	$237.373	$237.37	$237.35	$237.40
7 purchase totals =	$968.22		$1,050.5432	$1,050.54	$1,050.50	$1,050.50