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	$168.37	9.382%	$184.1665	$184.17	$184.15	$184.20
Purchase #2	$51.62	7.871%	$55.683	$55.68	$55.70	$55.70
Purchase #3	$246.26	9.754%	$270.2802	$270.28	$270.30	$270.30
Purchase #4	$141.61	3.373%	$146.3865	$146.39	$146.40	$146.40
Purchase #5	$167.89	7.453%	$180.4028	$180.40	$180.40	$180.40
Purchase #6	$156.29	7.870%	$168.59	$168.59	$168.60	$168.60
Purchase #7	$135.84	11.183%	$151.031	$151.03	$151.05	$151.00
7 purchase totals =	$1,067.88		$1,156.5400	$1,156.54	$1,156.60	$1,156.60