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	$44.59	6.856%	$47.6471	$47.65	$47.65	$47.60
Purchase #2	$196.68	4.438%	$205.4087	$205.41	$205.40	$205.40
Purchase #3	$211.64	3.193%	$218.3977	$218.40	$218.40	$218.40
Purchase #4	$202.33	12.364%	$227.3461	$227.35	$227.35	$227.30
Purchase #5	$86.64	11.538%	$96.6365	$96.64	$96.65	$96.60
Purchase #6	$247.95	12.309%	$278.4702	$278.47	$278.45	$278.50
Purchase #7	$105.76	5.780%	$111.8729	$111.87	$111.85	$111.90
7 purchase totals =	$1,095.59		$1,185.7792	$1,185.79	$1,185.75	$1,185.70