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	$174.28	12.442%	$195.9639	$195.96	$195.95	$196.00
Purchase #2	$123.71	6.616%	$131.8947	$131.89	$131.90	$131.90
Purchase #3	$233.89	10.371%	$258.1467	$258.15	$258.15	$258.10
Purchase #4	$53.47	5.298%	$56.3028	$56.30	$56.30	$56.30
Purchase #5	$246.42	8.793%	$268.0877	$268.09	$268.10	$268.10
Purchase #6	$182.86	3.413%	$189.101	$189.10	$189.10	$189.10
Purchase #7	$59.25	9.527%	$64.8947	$64.89	$64.90	$64.90
7 purchase totals =	$1,073.88		$1,164.3915	$1,164.38	$1,164.40	$1,164.40