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	$196.37	6.155%	$208.4566	$208.46	$208.45	$208.50
Purchase #2	$60.73	13.321%	$68.8198	$68.82	$68.80	$68.80
Purchase #3	$71.34	9.706%	$78.2643	$78.26	$78.25	$78.30
Purchase #4	$192.40	10.738%	$213.0599	$213.06	$213.05	$213.10
Purchase #5	$181.74	5.737%	$192.1664	$192.17	$192.15	$192.20
Purchase #6	$113.54	6.829%	$121.2936	$121.29	$121.30	$121.30
Purchase #7	$128.61	4.334%	$134.184	$134.18	$134.20	$134.20
7 purchase totals =	$944.73		$1,016.2446	$1,016.24	$1,016.20	$1,016.40