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	$42.75	5.115%	$44.9367	$44.94	$44.95	$44.90
Purchase #2	$112.77	11.659%	$125.9179	$125.92	$125.90	$125.90
Purchase #3	$233.75	12.308%	$262.52	$262.52	$262.50	$262.50
Purchase #4	$212.48	5.122%	$223.3632	$223.36	$223.35	$223.40
Purchase #5	$250.47	9.194%	$273.4982	$273.50	$273.50	$273.50
Purchase #6	$156.53	6.240%	$166.2975	$166.30	$166.30	$166.30
Purchase #7	$62.91	13.318%	$71.2884	$71.29	$71.30	$71.30
7 purchase totals =	$1,071.66		$1,167.8219	$1,167.83	$1,167.80	$1,167.80