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	$182.66	8.317%	$197.8518	$197.85	$197.85	$197.90
Purchase #2	$155.91	13.613%	$177.134	$177.13	$177.15	$177.10
Purchase #3	$105.80	3.213%	$109.1994	$109.20	$109.20	$109.20
Purchase #4	$66.86	9.118%	$72.9563	$72.96	$72.95	$73.00
Purchase #5	$226.88	13.155%	$256.7261	$256.73	$256.75	$256.70
Purchase #6	$37.35	13.673%	$42.4569	$42.46	$42.45	$42.50
Purchase #7	$219.33	4.178%	$228.4936	$228.49	$228.50	$228.50
7 purchase totals =	$994.79		$1,084.8181	$1,084.82	$1,084.85	$1,084.90