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	$97.56	8.683%	$106.0311	$106.03	$106.05	$106.00
Purchase #2	$160.92	5.417%	$169.637	$169.64	$169.65	$169.60
Purchase #3	$208.35	12.131%	$233.6249	$233.62	$233.60	$233.60
Purchase #4	$54.34	13.481%	$61.6656	$61.67	$61.65	$61.70
Purchase #5	$160.53	9.328%	$175.5042	$175.50	$175.50	$175.50
Purchase #6	$140.44	8.706%	$152.6667	$152.67	$152.65	$152.70
Purchase #7	$97.56	12.143%	$109.4067	$109.41	$109.40	$109.40
7 purchase totals =	$919.70		$1,008.5362	$1,008.54	$1,008.50	$1,008.50