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	$143.50	10.687%	$158.8358	$158.84	$158.85	$158.80
Purchase #2	$67.78	4.865%	$71.0775	$71.08	$71.10	$71.10
Purchase #3	$69.30	6.588%	$73.8655	$73.87	$73.85	$73.90
Purchase #4	$89.86	9.530%	$98.4237	$98.42	$98.40	$98.40
Purchase #5	$103.54	9.457%	$113.3318	$113.33	$113.35	$113.30
Purchase #6	$232.47	10.120%	$255.996	$256.00	$256.00	$256.00
Purchase #7	$238.34	10.273%	$262.8247	$262.82	$262.80	$262.80
7 purchase totals =	$944.79		$1,034.3550	$1,034.36	$1,034.35	$1,034.30