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	$126.56	4.185%	$131.8565	$131.86	$131.85	$131.90
Purchase #2	$203.74	3.474%	$210.8179	$210.82	$210.80	$210.80
Purchase #3	$11.93	3.181%	$12.3095	$12.31	$12.30	$12.30
Purchase #4	$99.50	5.474%	$104.9466	$104.95	$104.95	$104.90
Purchase #5	$161.74	6.568%	$172.3631	$172.36	$172.35	$172.40
Purchase #6	$245.71	7.546%	$264.2513	$264.25	$264.25	$264.30
Purchase #7	$202.63	8.362%	$219.5739	$219.57	$219.55	$219.60
7 purchase totals =	$1,051.81		$1,116.1188	$1,116.12	$1,116.05	$1,116.20