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	$243.95	7.627%	$262.5561	$262.56	$262.55	$262.60
Purchase #2	$143.89	11.561%	$160.5251	$160.53	$160.55	$160.50
Purchase #3	$70.98	10.261%	$78.2633	$78.26	$78.25	$78.30
Purchase #4	$72.93	6.670%	$77.7944	$77.79	$77.80	$77.80
Purchase #5	$53.34	3.381%	$55.1434	$55.14	$55.15	$55.10
Purchase #6	$81.96	7.452%	$88.0677	$88.07	$88.05	$88.10
Purchase #7	$168.26	13.498%	$190.9717	$190.97	$190.95	$191.00
7 purchase totals =	$835.31		$913.3217	$913.32	$913.30	$913.40