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	$89.44	7.149%	$95.8341	$95.83	$95.85	$95.80
Purchase #2	$43.35	10.229%	$47.7843	$47.78	$47.80	$47.80
Purchase #3	$216.93	5.669%	$229.2278	$229.23	$229.25	$229.20
Purchase #4	$248.29	3.144%	$256.0962	$256.10	$256.10	$256.10
Purchase #5	$157.66	5.153%	$165.7842	$165.78	$165.80	$165.80
Purchase #6	$29.64	10.797%	$32.8402	$32.84	$32.85	$32.80
Purchase #7	$94.27	3.667%	$97.7269	$97.73	$97.75	$97.70
7 purchase totals =	$879.58		$925.2937	$925.29	$925.40	$925.20