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	$146.30	4.324%	$152.626	$152.63	$152.65	$152.60
Purchase #2	$76.86	8.150%	$83.1241	$83.12	$83.10	$83.10
Purchase #3	$183.59	11.735%	$205.1343	$205.13	$205.15	$205.10
Purchase #4	$211.41	3.434%	$218.6698	$218.67	$218.65	$218.70
Purchase #5	$219.25	8.865%	$238.6865	$238.69	$238.70	$238.70
Purchase #6	$69.55	4.166%	$72.4475	$72.45	$72.45	$72.40
Purchase #7	$42.45	11.202%	$47.2052	$47.21	$47.20	$47.20
7 purchase totals =	$949.41		$1,017.8934	$1,017.90	$1,017.90	$1,017.80