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	$197.79	10.736%	$219.0247	$219.02	$219.00	$219.00
Purchase #2	$69.92	5.684%	$73.8943	$73.89	$73.90	$73.90
Purchase #3	$229.82	11.741%	$256.8032	$256.80	$256.80	$256.80
Purchase #4	$76.90	10.869%	$85.2583	$85.26	$85.25	$85.30
Purchase #5	$175.35	11.854%	$196.136	$196.14	$196.15	$196.10
Purchase #6	$155.39	10.582%	$171.8334	$171.83	$171.85	$171.80
Purchase #7	$37.36	10.141%	$41.1487	$41.15	$41.15	$41.10
7 purchase totals =	$942.53		$1,044.0986	$1,044.09	$1,044.10	$1,044.00