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	$160.98	8.528%	$174.7084	$174.71	$174.70	$174.70
Purchase #2	$27.25	4.640%	$28.5144	$28.51	$28.50	$28.50
Purchase #3	$157.93	6.466%	$168.1418	$168.14	$168.15	$168.10
Purchase #4	$194.68	8.684%	$211.586	$211.59	$211.60	$211.60
Purchase #5	$93.28	6.430%	$99.2779	$99.28	$99.30	$99.30
Purchase #6	$133.60	12.330%	$150.0729	$150.07	$150.05	$150.10
Purchase #7	$188.81	6.337%	$200.7749	$200.77	$200.75	$200.80
7 purchase totals =	$956.53		$1,033.0763	$1,033.07	$1,033.05	$1,033.10