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	$171.62	11.260%	$190.9444	$190.94	$190.95	$190.90
Purchase #2	$162.64	12.352%	$182.7293	$182.73	$182.75	$182.70
Purchase #3	$165.28	4.673%	$173.0035	$173.00	$173.00	$173.00
Purchase #4	$169.34	9.687%	$185.744	$185.74	$185.75	$185.70
Purchase #5	$83.89	3.139%	$86.5233	$86.52	$86.50	$86.50
Purchase #6	$171.49	11.411%	$191.0587	$191.06	$191.05	$191.10
Purchase #7	$38.77	12.465%	$43.6027	$43.60	$43.60	$43.60
7 purchase totals =	$963.03		$1,053.6059	$1,053.59	$1,053.60	$1,053.50