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	$198.35	7.167%	$212.5657	$212.57	$212.55	$212.60
Purchase #2	$95.51	7.185%	$102.3724	$102.37	$102.35	$102.40
Purchase #3	$72.35	12.162%	$81.1492	$81.15	$81.15	$81.10
Purchase #4	$203.32	6.266%	$216.06	$216.06	$216.05	$216.10
Purchase #5	$62.50	3.255%	$64.5344	$64.53	$64.55	$64.50
Purchase #6	$98.97	6.642%	$105.5436	$105.54	$105.55	$105.50
Purchase #7	$39.44	9.804%	$43.3067	$43.31	$43.30	$43.30
7 purchase totals =	$770.44		$825.5320	$825.53	$825.50	$825.50