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	$203.82	7.542%	$219.1921	$219.19	$219.20	$219.20
Purchase #2	$66.67	5.398%	$70.2688	$70.27	$70.25	$70.30
Purchase #3	$60.48	10.681%	$66.9399	$66.94	$66.95	$66.90
Purchase #4	$211.28	3.613%	$218.9135	$218.91	$218.90	$218.90
Purchase #5	$78.81	13.838%	$89.7157	$89.72	$89.70	$89.70
Purchase #6	$234.88	12.195%	$263.5236	$263.52	$263.50	$263.50
Purchase #7	$166.97	11.106%	$185.5137	$185.51	$185.50	$185.50
7 purchase totals =	$1,022.91		$1,114.0673	$1,114.06	$1,114.00	$1,114.00