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	$131.97	8.126%	$142.6939	$142.69	$142.70	$142.70
Purchase #2	$232.89	7.825%	$251.1136	$251.11	$251.10	$251.10
Purchase #3	$120.92	8.465%	$131.1559	$131.16	$131.15	$131.20
Purchase #4	$144.54	9.805%	$158.7121	$158.71	$158.70	$158.70
Purchase #5	$215.92	13.656%	$245.406	$245.41	$245.40	$245.40
Purchase #6	$73.63	13.126%	$83.2947	$83.29	$83.30	$83.30
Purchase #7	$77.56	6.250%	$82.4075	$82.41	$82.40	$82.40
7 purchase totals =	$997.43		$1,094.7837	$1,094.78	$1,094.75	$1,094.80