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	$55.86	6.816%	$59.6674	$59.67	$59.65	$59.70
Purchase #2	$69.48	11.632%	$77.5619	$77.56	$77.55	$77.60
Purchase #3	$240.64	6.226%	$255.6222	$255.62	$255.60	$255.60
Purchase #4	$237.83	7.541%	$255.7648	$255.76	$255.75	$255.80
Purchase #5	$240.93	6.358%	$256.2483	$256.25	$256.25	$256.20
Purchase #6	$168.31	7.625%	$181.1436	$181.14	$181.15	$181.10
Purchase #7	$90.62	6.183%	$96.223	$96.22	$96.20	$96.20
7 purchase totals =	$1,103.67		$1,182.2312	$1,182.22	$1,182.15	$1,182.20