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	$104.64	5.514%	$110.4098	$110.41	$110.40	$110.40
Purchase #2	$64.35	5.512%	$67.897	$67.90	$67.90	$67.90
Purchase #3	$116.48	10.192%	$128.3516	$128.35	$128.35	$128.40
Purchase #4	$127.28	12.653%	$143.3847	$143.38	$143.40	$143.40
Purchase #5	$199.86	6.541%	$212.9328	$212.93	$212.95	$212.90
Purchase #6	$155.86	5.694%	$164.7347	$164.73	$164.75	$164.70
Purchase #7	$193.28	8.380%	$209.4769	$209.48	$209.50	$209.50
7 purchase totals =	$961.75		$1,037.1875	$1,037.18	$1,037.25	$1,037.20