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	$201.81	6.727%	$215.3858	$215.39	$215.40	$215.40
Purchase #2	$196.94	7.138%	$210.9976	$211.00	$211.00	$211.00
Purchase #3	$53.74	10.282%	$59.2655	$59.27	$59.25	$59.30
Purchase #4	$223.95	13.186%	$253.48	$253.48	$253.50	$253.50
Purchase #5	$54.50	13.792%	$62.0166	$62.02	$62.00	$62.00
Purchase #6	$167.31	5.274%	$176.1339	$176.13	$176.15	$176.10
Purchase #7	$172.73	5.444%	$182.1334	$182.13	$182.15	$182.10
7 purchase totals =	$1,070.98		$1,159.4128	$1,159.42	$1,159.45	$1,159.40