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	$55.64	11.860%	$62.2389	$62.24	$62.25	$62.20
Purchase #2	$30.42	10.365%	$33.573	$33.57	$33.55	$33.60
Purchase #3	$85.83	10.680%	$94.9966	$95.00	$95.00	$95.00
Purchase #4	$142.45	8.578%	$154.6694	$154.67	$154.65	$154.70
Purchase #5	$16.25	13.839%	$18.4988	$18.50	$18.50	$18.50
Purchase #6	$239.80	10.249%	$264.3771	$264.38	$264.40	$264.40
Purchase #7	$70.47	11.115%	$78.3027	$78.30	$78.30	$78.30
7 purchase totals =	$640.86		$706.6565	$706.66	$706.65	$706.70