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	$212.45	12.469%	$238.9404	$238.94	$238.95	$238.90
Purchase #2	$189.39	3.481%	$195.9827	$195.98	$196.00	$196.00
Purchase #3	$12.50	4.810%	$13.1013	$13.10	$13.10	$13.10
Purchase #4	$193.99	11.282%	$215.876	$215.88	$215.90	$215.90
Purchase #5	$202.37	13.214%	$229.1112	$229.11	$229.10	$229.10
Purchase #6	$73.96	11.378%	$82.3752	$82.38	$82.40	$82.40
Purchase #7	$128.95	3.645%	$133.6502	$133.65	$133.65	$133.70
7 purchase totals =	$1,013.61		$1,109.0370	$1,109.04	$1,109.10	$1,109.10