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	$171.75	12.172%	$192.6554	$192.66	$192.65	$192.70
Purchase #2	$13.31	7.773%	$14.3446	$14.34	$14.35	$14.30
Purchase #3	$55.56	7.178%	$59.5481	$59.55	$59.55	$59.50
Purchase #4	$32.96	12.729%	$37.1555	$37.16	$37.15	$37.20
Purchase #5	$227.93	13.740%	$259.2476	$259.25	$259.25	$259.20
Purchase #6	$146.42	7.486%	$157.381	$157.38	$157.40	$157.40
Purchase #7	$25.59	9.577%	$28.0408	$28.04	$28.05	$28.00
7 purchase totals =	$673.52		$748.3730	$748.38	$748.40	$748.30