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	$113.91	11.692%	$127.2284	$127.23	$127.25	$127.20
Purchase #2	$159.47	9.111%	$173.9993	$174.00	$174.00	$174.00
Purchase #3	$24.51	11.495%	$27.3274	$27.33	$27.35	$27.30
Purchase #4	$176.78	6.844%	$188.8788	$188.88	$188.90	$188.90
Purchase #5	$236.67	13.457%	$268.5187	$268.52	$268.50	$268.50
Purchase #6	$29.81	5.858%	$31.5563	$31.56	$31.55	$31.60
Purchase #7	$241.38	10.726%	$267.2704	$267.27	$267.25	$267.30
7 purchase totals =	$982.53		$1,084.7793	$1,084.79	$1,084.80	$1,084.80