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	$43.67	7.759%	$47.0584	$47.06	$47.05	$47.10
Purchase #2	$120.60	6.327%	$128.2304	$128.23	$128.25	$128.20
Purchase #3	$72.58	11.659%	$81.0421	$81.04	$81.05	$81.00
Purchase #4	$33.67	11.678%	$37.602	$37.60	$37.60	$37.60
Purchase #5	$152.73	9.675%	$167.5066	$167.51	$167.50	$167.50
Purchase #6	$19.58	5.833%	$20.7221	$20.72	$20.70	$20.70
Purchase #7	$206.51	4.825%	$216.4741	$216.47	$216.45	$216.50
7 purchase totals =	$649.34		$698.6357	$698.63	$698.60	$698.60