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	$59.73	5.245%	$62.8628	$62.86	$62.85	$62.90
Purchase #2	$136.30	8.177%	$147.4453	$147.45	$147.45	$147.40
Purchase #3	$164.54	4.775%	$172.3968	$172.40	$172.40	$172.40
Purchase #4	$42.80	3.556%	$44.322	$44.32	$44.30	$44.30
Purchase #5	$106.61	6.156%	$113.1729	$113.17	$113.15	$113.20
Purchase #6	$154.30	11.148%	$171.5014	$171.50	$171.50	$171.50
Purchase #7	$36.77	12.486%	$41.3611	$41.36	$41.35	$41.40
7 purchase totals =	$701.05		$753.0623	$753.06	$753.00	$753.10