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	$90.78	6.813%	$96.9648	$96.96	$96.95	$97.00
Purchase #2	$152.38	6.658%	$162.5255	$162.53	$162.55	$162.50
Purchase #3	$63.37	3.556%	$65.6234	$65.62	$65.60	$65.60
Purchase #4	$220.58	13.490%	$250.3362	$250.34	$250.35	$250.30
Purchase #5	$78.85	8.836%	$85.8172	$85.82	$85.80	$85.80
Purchase #6	$224.78	7.829%	$242.378	$242.38	$242.40	$242.40
Purchase #7	$102.62	3.825%	$106.5452	$106.55	$106.55	$106.50
7 purchase totals =	$933.36		$1,010.1903	$1,010.20	$1,010.20	$1,010.10