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	$160.51	7.758%	$172.9624	$172.96	$172.95	$173.00
Purchase #2	$9.85	3.592%	$10.2038	$10.20	$10.20	$10.20
Purchase #3	$9.94	5.684%	$10.505	$10.51	$10.50	$10.50
Purchase #4	$31.36	6.249%	$33.3197	$33.32	$33.30	$33.30
Purchase #5	$135.28	11.358%	$150.6451	$150.65	$150.65	$150.60
Purchase #6	$148.94	7.207%	$159.6741	$159.67	$159.65	$159.70
Purchase #7	$173.50	13.451%	$196.8375	$196.84	$196.85	$196.80
7 purchase totals =	$669.38		$734.1476	$734.15	$734.10	$734.10