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	$147.64	4.266%	$153.9383	$153.94	$153.95	$153.90
Purchase #2	$99.61	12.147%	$111.7096	$111.71	$111.70	$111.70
Purchase #3	$103.97	5.137%	$109.3109	$109.31	$109.30	$109.30
Purchase #4	$191.62	10.391%	$211.5312	$211.53	$211.55	$211.50
Purchase #5	$99.33	7.236%	$106.5175	$106.52	$106.50	$106.50
Purchase #6	$58.93	13.602%	$66.9457	$66.95	$66.95	$66.90
Purchase #7	$106.38	8.457%	$115.3766	$115.38	$115.40	$115.40
7 purchase totals =	$807.48		$875.3298	$875.34	$875.35	$875.20