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	$141.41	10.824%	$156.7162	$156.72	$156.70	$156.70
Purchase #2	$161.32	11.345%	$179.6218	$179.62	$179.60	$179.60
Purchase #3	$50.90	9.157%	$55.5609	$55.56	$55.55	$55.60
Purchase #4	$218.29	8.272%	$236.3469	$236.35	$236.35	$236.30
Purchase #5	$62.31	6.789%	$66.5402	$66.54	$66.55	$66.50
Purchase #6	$211.99	3.600%	$219.6216	$219.62	$219.60	$219.60
Purchase #7	$164.65	10.211%	$181.4624	$181.46	$181.45	$181.50
7 purchase totals =	$1,010.87		$1,095.8700	$1,095.87	$1,095.80	$1,095.80