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	$176.93	7.527%	$190.2475	$190.25	$190.25	$190.20
Purchase #2	$204.78	3.718%	$212.3937	$212.39	$212.40	$212.40
Purchase #3	$41.66	6.377%	$44.3167	$44.32	$44.30	$44.30
Purchase #4	$209.59	4.597%	$219.2249	$219.22	$219.20	$219.20
Purchase #5	$160.46	4.179%	$167.1656	$167.17	$167.15	$167.20
Purchase #6	$94.84	11.207%	$105.4687	$105.47	$105.45	$105.50
Purchase #7	$55.41	13.193%	$62.7202	$62.72	$62.70	$62.70
7 purchase totals =	$943.67		$1,001.5373	$1,001.54	$1,001.45	$1,001.50