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	$70.38	3.360%	$72.7448	$72.74	$72.75	$72.70
Purchase #2	$77.68	10.336%	$85.709	$85.71	$85.70	$85.70
Purchase #3	$96.40	4.453%	$100.6927	$100.69	$100.70	$100.70
Purchase #4	$99.89	12.357%	$112.2334	$112.23	$112.25	$112.20
Purchase #5	$189.82	4.208%	$197.8076	$197.81	$197.80	$197.80
Purchase #6	$190.66	9.766%	$209.2799	$209.28	$209.30	$209.30
Purchase #7	$228.33	7.730%	$245.9799	$245.98	$246.00	$246.00
7 purchase totals =	$953.16		$1,024.4473	$1,024.44	$1,024.50	$1,024.40