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	$195.28	5.252%	$205.5361	$205.54	$205.55	$205.50
Purchase #2	$178.58	4.437%	$186.5036	$186.50	$186.50	$186.50
Purchase #3	$180.95	12.270%	$203.1526	$203.15	$203.15	$203.20
Purchase #4	$234.60	4.222%	$244.5048	$244.50	$244.50	$244.50
Purchase #5	$119.54	11.519%	$133.3098	$133.31	$133.30	$133.30
Purchase #6	$76.25	3.525%	$78.9378	$78.94	$78.95	$78.90
Purchase #7	$165.58	13.740%	$188.3307	$188.33	$188.35	$188.30
7 purchase totals =	$1,150.78		$1,240.2754	$1,240.27	$1,240.30	$1,240.20