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	$201.58	4.412%	$210.4737	$210.47	$210.45	$210.50
Purchase #2	$244.81	4.355%	$255.4715	$255.47	$255.45	$255.50
Purchase #3	$99.53	13.608%	$113.074	$113.07	$113.05	$113.10
Purchase #4	$164.77	4.702%	$172.5175	$172.52	$172.50	$172.50
Purchase #5	$133.64	10.669%	$147.8981	$147.90	$147.90	$147.90
Purchase #6	$194.80	8.617%	$211.5859	$211.59	$211.60	$211.60
Purchase #7	$144.29	7.301%	$154.8246	$154.82	$154.80	$154.80
7 purchase totals =	$1,183.42		$1,265.8453	$1,265.84	$1,265.75	$1,265.90