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	$103.69	6.562%	$110.4941	$110.49	$110.50	$110.50
Purchase #2	$16.89	13.524%	$19.1742	$19.17	$19.15	$19.20
Purchase #3	$42.93	8.768%	$46.6941	$46.69	$46.70	$46.70
Purchase #4	$143.72	7.417%	$154.3797	$154.38	$154.40	$154.40
Purchase #5	$172.90	6.447%	$184.0469	$184.05	$184.05	$184.00
Purchase #6	$147.38	3.141%	$152.0092	$152.01	$152.00	$152.00
Purchase #7	$100.72	4.719%	$105.473	$105.47	$105.45	$105.50
7 purchase totals =	$728.23		$772.2712	$772.26	$772.25	$772.30