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	$194.69	13.334%	$220.65	$220.65	$220.65	$220.70
Purchase #2	$35.90	7.502%	$38.5932	$38.59	$38.60	$38.60
Purchase #3	$107.32	3.823%	$111.4228	$111.42	$111.40	$111.40
Purchase #4	$28.65	10.501%	$31.6585	$31.66	$31.65	$31.70
Purchase #5	$222.31	11.778%	$248.4937	$248.49	$248.50	$248.50
Purchase #6	$198.42	6.267%	$210.855	$210.86	$210.85	$210.90
Purchase #7	$229.39	3.214%	$236.7626	$236.76	$236.75	$236.80
7 purchase totals =	$1,016.68		$1,098.4358	$1,098.43	$1,098.40	$1,098.60