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	$191.98	4.505%	$200.6287	$200.63	$200.65	$200.60
Purchase #2	$216.34	3.161%	$223.1785	$223.18	$223.20	$223.20
Purchase #3	$150.72	4.124%	$156.9357	$156.94	$156.95	$156.90
Purchase #4	$169.26	6.206%	$179.7643	$179.76	$179.75	$179.80
Purchase #5	$55.49	4.236%	$57.8406	$57.84	$57.85	$57.80
Purchase #6	$50.29	8.229%	$54.4284	$54.43	$54.45	$54.40
Purchase #7	$153.84	5.645%	$162.5243	$162.52	$162.50	$162.50
7 purchase totals =	$987.92		$1,035.3005	$1,035.30	$1,035.35	$1,035.20