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	$177.66	10.868%	$196.9681	$196.97	$196.95	$197.00
Purchase #2	$59.59	11.268%	$66.3046	$66.30	$66.30	$66.30
Purchase #3	$206.42	4.700%	$216.1217	$216.12	$216.10	$216.10
Purchase #4	$246.59	7.227%	$264.4111	$264.41	$264.40	$264.40
Purchase #5	$222.58	10.764%	$246.5385	$246.54	$246.55	$246.50
Purchase #6	$69.70	5.744%	$73.7036	$73.70	$73.70	$73.70
Purchase #7	$74.41	5.639%	$78.606	$78.61	$78.60	$78.60
7 purchase totals =	$1,056.95		$1,142.6536	$1,142.65	$1,142.60	$1,142.60