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	$168.68	12.672%	$190.0551	$190.06	$190.05	$190.10
Purchase #2	$85.55	8.473%	$92.7987	$92.80	$92.80	$92.80
Purchase #3	$72.69	7.361%	$78.0407	$78.04	$78.05	$78.00
Purchase #4	$229.39	8.835%	$249.6566	$249.66	$249.65	$249.70
Purchase #5	$107.38	5.536%	$113.3246	$113.32	$113.30	$113.30
Purchase #6	$78.99	4.607%	$82.6291	$82.63	$82.65	$82.60
Purchase #7	$200.30	9.589%	$219.5068	$219.51	$219.50	$219.50
7 purchase totals =	$942.98		$1,026.0116	$1,026.02	$1,026.00	$1,026.00