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	$191.58	3.847%	$198.9501	$198.95	$198.95	$199.00
Purchase #2	$164.38	13.413%	$186.4283	$186.43	$186.45	$186.40
Purchase #3	$41.75	3.467%	$43.1975	$43.20	$43.20	$43.20
Purchase #4	$234.47	13.220%	$265.4669	$265.47	$265.45	$265.50
Purchase #5	$79.39	4.393%	$82.8776	$82.88	$82.90	$82.90
Purchase #6	$219.34	7.280%	$235.308	$235.31	$235.30	$235.30
Purchase #7	$12.49	6.568%	$13.3103	$13.31	$13.30	$13.30
7 purchase totals =	$943.40		$1,025.5387	$1,025.55	$1,025.55	$1,025.60