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	$188.34	4.361%	$196.5535	$196.55	$196.55	$196.60
Purchase #2	$123.31	6.264%	$131.0341	$131.03	$131.05	$131.00
Purchase #3	$72.84	4.252%	$75.9372	$75.94	$75.95	$75.90
Purchase #4	$195.98	6.241%	$208.2111	$208.21	$208.20	$208.20
Purchase #5	$126.46	6.294%	$134.4194	$134.42	$134.40	$134.40
Purchase #6	$182.34	12.348%	$204.8553	$204.86	$204.85	$204.90
Purchase #7	$132.93	11.449%	$148.1492	$148.15	$148.15	$148.10
7 purchase totals =	$1,022.20		$1,099.1598	$1,099.16	$1,099.15	$1,099.10