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	$175.81	10.535%	$194.3316	$194.33	$194.35	$194.30
Purchase #2	$20.77	5.284%	$21.8675	$21.87	$21.85	$21.90
Purchase #3	$246.40	7.265%	$264.301	$264.30	$264.30	$264.30
Purchase #4	$133.27	3.796%	$138.3289	$138.33	$138.35	$138.30
Purchase #5	$70.79	13.736%	$80.5137	$80.51	$80.50	$80.50
Purchase #6	$196.80	6.398%	$209.3913	$209.39	$209.40	$209.40
Purchase #7	$128.47	4.221%	$133.8927	$133.89	$133.90	$133.90
7 purchase totals =	$972.31		$1,042.6267	$1,042.62	$1,042.65	$1,042.60