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	$174.47	13.401%	$197.8507	$197.85	$197.85	$197.90
Purchase #2	$37.79	6.541%	$40.2618	$40.26	$40.25	$40.30
Purchase #3	$126.83	6.127%	$134.6009	$134.60	$134.60	$134.60
Purchase #4	$16.32	13.107%	$18.4591	$18.46	$18.45	$18.50
Purchase #5	$228.33	5.740%	$241.4361	$241.44	$241.45	$241.40
Purchase #6	$210.49	6.154%	$223.4436	$223.44	$223.45	$223.40
Purchase #7	$182.97	7.408%	$196.5244	$196.52	$196.50	$196.50
7 purchase totals =	$977.20		$1,052.5766	$1,052.57	$1,052.55	$1,052.60