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	$104.30	9.349%	$114.051	$114.05	$114.05	$114.10
Purchase #2	$219.68	12.649%	$247.4673	$247.47	$247.45	$247.50
Purchase #3	$28.37	10.611%	$31.3803	$31.38	$31.40	$31.40
Purchase #4	$146.26	4.399%	$152.694	$152.69	$152.70	$152.70
Purchase #5	$168.55	12.386%	$189.4266	$189.43	$189.45	$189.40
Purchase #6	$175.44	8.825%	$190.9226	$190.92	$190.90	$190.90
Purchase #7	$83.74	6.733%	$89.3782	$89.38	$89.40	$89.40
7 purchase totals =	$926.34		$1,015.3200	$1,015.32	$1,015.35	$1,015.40