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	$119.60	4.821%	$125.3659	$125.37	$125.35	$125.40
Purchase #2	$157.82	13.540%	$179.1888	$179.19	$179.20	$179.20
Purchase #3	$139.74	11.695%	$156.0826	$156.08	$156.10	$156.10
Purchase #4	$91.53	9.463%	$100.1915	$100.19	$100.20	$100.20
Purchase #5	$186.75	5.412%	$196.8569	$196.86	$196.85	$196.90
Purchase #6	$86.69	5.281%	$91.2681	$91.27	$91.25	$91.30
Purchase #7	$211.25	8.652%	$229.5274	$229.53	$229.55	$229.50
7 purchase totals =	$993.38		$1,078.4812	$1,078.49	$1,078.50	$1,078.60