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	$172.47	7.469%	$185.3518	$185.35	$185.35	$185.40
Purchase #2	$241.59	6.547%	$257.4069	$257.41	$257.40	$257.40
Purchase #3	$59.45	3.324%	$61.4261	$61.43	$61.45	$61.40
Purchase #4	$30.33	3.546%	$31.4055	$31.41	$31.40	$31.40
Purchase #5	$40.53	4.650%	$42.4146	$42.41	$42.40	$42.40
Purchase #6	$127.59	7.172%	$136.7408	$136.74	$136.75	$136.70
Purchase #7	$36.30	7.514%	$39.0276	$39.03	$39.05	$39.00
7 purchase totals =	$708.26		$753.7733	$753.78	$753.80	$753.70