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	$191.77	7.596%	$206.3368	$206.34	$206.35	$206.30
Purchase #2	$50.63	5.817%	$53.5751	$53.58	$53.60	$53.60
Purchase #3	$81.85	9.760%	$89.8386	$89.84	$89.85	$89.80
Purchase #4	$230.76	11.481%	$257.2536	$257.25	$257.25	$257.30
Purchase #5	$153.42	9.442%	$167.9059	$167.91	$167.90	$167.90
Purchase #6	$89.77	4.128%	$93.4757	$93.48	$93.50	$93.50
Purchase #7	$209.84	8.423%	$227.5148	$227.51	$227.50	$227.50
7 purchase totals =	$1,008.04		$1,095.9005	$1,095.91	$1,095.95	$1,095.90