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	$117.95	5.350%	$124.2603	$124.26	$124.25	$124.30
Purchase #2	$139.43	10.241%	$153.709	$153.71	$153.70	$153.70
Purchase #3	$76.51	7.477%	$82.2307	$82.23	$82.25	$82.20
Purchase #4	$222.91	5.125%	$234.3341	$234.33	$234.35	$234.30
Purchase #5	$118.57	7.332%	$127.2636	$127.26	$127.25	$127.30
Purchase #6	$102.83	6.770%	$109.7916	$109.79	$109.80	$109.80
Purchase #7	$199.59	8.420%	$216.3955	$216.40	$216.40	$216.40
7 purchase totals =	$977.79		$1,047.9848	$1,047.98	$1,048.00	$1,048.00