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	$195.31	10.668%	$216.1457	$216.15	$216.15	$216.10
Purchase #2	$70.55	11.294%	$78.5179	$78.52	$78.50	$78.50
Purchase #3	$226.56	6.608%	$241.5311	$241.53	$241.55	$241.50
Purchase #4	$241.63	13.607%	$274.5086	$274.51	$274.50	$274.50
Purchase #5	$215.52	13.313%	$244.2122	$244.21	$244.20	$244.20
Purchase #6	$38.30	12.292%	$43.0078	$43.01	$43.00	$43.00
Purchase #7	$18.94	13.681%	$21.5312	$21.53	$21.55	$21.50
7 purchase totals =	$1,006.81		$1,119.4545	$1,119.46	$1,119.45	$1,119.30