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	$191.53	9.774%	$210.2501	$210.25	$210.25	$210.30
Purchase #2	$169.51	3.307%	$175.1157	$175.12	$175.10	$175.10
Purchase #3	$190.65	3.103%	$196.5659	$196.57	$196.55	$196.60
Purchase #4	$186.45	12.666%	$210.0658	$210.07	$210.05	$210.10
Purchase #5	$209.55	3.830%	$217.5758	$217.58	$217.60	$217.60
Purchase #6	$73.58	6.647%	$78.4709	$78.47	$78.45	$78.50
Purchase #7	$90.46	7.120%	$96.9008	$96.90	$96.90	$96.90
7 purchase totals =	$1,111.73		$1,184.9450	$1,184.96	$1,184.90	$1,185.10