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	$189.47	3.742%	$196.56	$196.56	$196.55	$196.60
Purchase #2	$198.44	12.791%	$223.8225	$223.82	$223.80	$223.80
Purchase #3	$62.97	7.588%	$67.7482	$67.75	$67.75	$67.70
Purchase #4	$194.49	12.742%	$219.2719	$219.27	$219.25	$219.30
Purchase #5	$138.31	7.599%	$148.8202	$148.82	$148.80	$148.80
Purchase #6	$15.73	4.867%	$16.4956	$16.50	$16.50	$16.50
Purchase #7	$174.50	6.774%	$186.3206	$186.32	$186.30	$186.30
7 purchase totals =	$973.91		$1,059.0390	$1,059.04	$1,058.95	$1,059.00