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	$231.76	7.546%	$249.2486	$249.25	$249.25	$249.20
Purchase #2	$197.64	7.438%	$212.3405	$212.34	$212.35	$212.30
Purchase #3	$148.83	5.431%	$156.913	$156.91	$156.90	$156.90
Purchase #4	$205.99	6.304%	$218.9756	$218.98	$219.00	$219.00
Purchase #5	$11.89	5.440%	$12.5368	$12.54	$12.55	$12.50
Purchase #6	$167.66	10.663%	$185.5376	$185.54	$185.55	$185.50
Purchase #7	$60.86	11.158%	$67.6508	$67.65	$67.65	$67.70
7 purchase totals =	$1,024.63		$1,103.2029	$1,103.21	$1,103.25	$1,103.10