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	$176.28	13.194%	$199.5384	$199.54	$199.55	$199.50
Purchase #2	$238.74	13.603%	$271.2158	$271.22	$271.20	$271.20
Purchase #3	$35.90	13.309%	$40.6779	$40.68	$40.70	$40.70
Purchase #4	$141.48	13.171%	$160.1143	$160.11	$160.10	$160.10
Purchase #5	$83.40	3.524%	$86.339	$86.34	$86.35	$86.30
Purchase #6	$144.88	13.770%	$164.83	$164.83	$164.85	$164.80
Purchase #7	$133.31	13.770%	$151.6668	$151.67	$151.65	$151.70
7 purchase totals =	$953.99		$1,074.3822	$1,074.39	$1,074.40	$1,074.30