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	$194.94	7.285%	$209.1414	$209.14	$209.15	$209.10
Purchase #2	$68.67	5.412%	$72.3864	$72.39	$72.40	$72.40
Purchase #3	$203.89	12.622%	$229.625	$229.63	$229.65	$229.60
Purchase #4	$66.74	5.800%	$70.6109	$70.61	$70.60	$70.60
Purchase #5	$76.56	7.489%	$82.2936	$82.29	$82.30	$82.30
Purchase #6	$122.33	6.377%	$130.131	$130.13	$130.15	$130.10
Purchase #7	$30.29	7.358%	$32.5187	$32.52	$32.50	$32.50
7 purchase totals =	$763.42		$826.7070	$826.71	$826.75	$826.60