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	$219.56	9.792%	$241.0593	$241.06	$241.05	$241.10
Purchase #2	$78.64	3.681%	$81.5347	$81.53	$81.55	$81.50
Purchase #3	$233.51	11.510%	$260.387	$260.39	$260.40	$260.40
Purchase #4	$97.86	7.706%	$105.4011	$105.40	$105.40	$105.40
Purchase #5	$215.83	7.515%	$232.0496	$232.05	$232.05	$232.00
Purchase #6	$181.33	11.172%	$201.5882	$201.59	$201.60	$201.60
Purchase #7	$75.61	3.807%	$78.4885	$78.49	$78.50	$78.50
7 purchase totals =	$1,102.34		$1,200.5084	$1,200.51	$1,200.55	$1,200.50