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	$192.43	6.677%	$205.2786	$205.28	$205.30	$205.30
Purchase #2	$24.68	12.602%	$27.7902	$27.79	$27.80	$27.80
Purchase #3	$186.88	7.482%	$200.8624	$200.86	$200.85	$200.90
Purchase #4	$196.84	8.445%	$213.4631	$213.46	$213.45	$213.50
Purchase #5	$129.73	10.365%	$143.1765	$143.18	$143.20	$143.20
Purchase #6	$81.82	10.633%	$90.5199	$90.52	$90.50	$90.50
Purchase #7	$136.54	5.399%	$143.9118	$143.91	$143.90	$143.90
7 purchase totals =	$948.92		$1,025.0025	$1,025.00	$1,025.00	$1,025.10