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	$228.82	7.231%	$245.366	$245.37	$245.35	$245.40
Purchase #2	$141.27	7.125%	$151.3355	$151.34	$151.35	$151.30
Purchase #3	$70.34	4.538%	$73.532	$73.53	$73.55	$73.50
Purchase #4	$72.64	8.369%	$78.7192	$78.72	$78.70	$78.70
Purchase #5	$221.31	7.706%	$238.3641	$238.36	$238.35	$238.40
Purchase #6	$244.44	7.151%	$261.9199	$261.92	$261.90	$261.90
Purchase #7	$83.40	12.566%	$93.88	$93.88	$93.90	$93.90
7 purchase totals =	$1,062.22		$1,143.1167	$1,143.12	$1,143.10	$1,143.10