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	$244.85	7.777%	$263.892	$263.89	$263.90	$263.90
Purchase #2	$65.59	3.566%	$67.9289	$67.93	$67.95	$67.90
Purchase #3	$221.34	9.399%	$242.1437	$242.14	$242.15	$242.10
Purchase #4	$89.35	4.506%	$93.3761	$93.38	$93.40	$93.40
Purchase #5	$163.94	8.791%	$178.352	$178.35	$178.35	$178.40
Purchase #6	$71.87	8.218%	$77.7763	$77.78	$77.80	$77.80
Purchase #7	$112.43	13.813%	$127.96	$127.96	$127.95	$128.00
7 purchase totals =	$969.37		$1,051.4290	$1,051.43	$1,051.50	$1,051.50