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	$98.66	6.662%	$105.2327	$105.23	$105.25	$105.20
Purchase #2	$156.57	6.600%	$166.9036	$166.90	$166.90	$166.90
Purchase #3	$97.57	6.160%	$103.5803	$103.58	$103.60	$103.60
Purchase #4	$223.90	9.514%	$245.2018	$245.20	$245.20	$245.20
Purchase #5	$99.44	8.263%	$107.6567	$107.66	$107.65	$107.70
Purchase #6	$184.48	6.712%	$196.8623	$196.86	$196.85	$196.90
Purchase #7	$201.53	7.226%	$216.0926	$216.09	$216.10	$216.10
7 purchase totals =	$1,062.15		$1,141.5300	$1,141.52	$1,141.55	$1,141.60