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	$58.54	7.236%	$62.776	$62.78	$62.80	$62.80
Purchase #2	$198.58	11.814%	$222.0402	$222.04	$222.05	$222.00
Purchase #3	$51.43	3.360%	$53.158	$53.16	$53.15	$53.20
Purchase #4	$119.90	9.805%	$131.6562	$131.66	$131.65	$131.70
Purchase #5	$210.56	12.751%	$237.4085	$237.41	$237.40	$237.40
Purchase #6	$188.40	11.592%	$210.2393	$210.24	$210.25	$210.20
Purchase #7	$47.42	3.523%	$49.0906	$49.09	$49.10	$49.10
7 purchase totals =	$874.83		$966.3688	$966.38	$966.40	$966.40